patch bump

simplifications
distinguish between default and user supplied tolerance
2026-04-20 00:15:11 +10:00 · 2026-04-19 22:59:46 +10:00 · 2026-04-18 23:48:32 +10:00 · 2026-04-18 17:45:48 +10:00 · 2026-04-18 17:09:20 +10:00 · 2026-04-18 17:08:51 +10:00
56 changed files with 1795 additions and 899 deletions
@@ -1,7 +1,7 @@
 Armadillo C++ Linear Algebra Library
-Copyright 2008-2025 Conrad Sanderson (https://conradsanderson.id.au)
+Copyright 2008-2026 Conrad Sanderson (https://conradsanderson.id.au)
 Copyright 2008-2016 National ICT Australia (NICTA)
-Copyright 2017-2025 Data61 / CSIRO
+Copyright 2017-2026 Data61 / CSIRO

 This product includes software developed by Conrad Sanderson (https://conradsanderson.id.au)
 This product includes software developed at National ICT Australia (NICTA)
@@ -1,9 +1,9 @@
 ### Armadillo: C++ Library for Linear Algebra & Scientific Computing  
 https://arma.sourceforge.net

-Copyright 2008-2025 Conrad Sanderson (https://conradsanderson.id.au)  
+Copyright 2008-2026 Conrad Sanderson (https://conradsanderson.id.au)  
 Copyright 2008-2016 National ICT Australia (NICTA)  
-Copyright 2017-2025 Data61 / CSIRO  
+Copyright 2017-2026 Data61 / CSIRO  

 ---

@@ -254,8 +254,9 @@ Conrad Sanderson and Ryan Curtin.
 <tr><td><a href="#Col">Col&lt;<i>type</i>&gt;, colvec, vec</a></td><td>&nbsp;</td><td>dense column vector class</td></tr>
 <tr><td><a href="#Row">Row&lt;<i>type</i>&gt;, rowvec</a></td><td>&nbsp;</td><td>dense row vector class</td></tr>
 <tr><td>&nbsp;</td><td>&nbsp;</td><td>&nbsp;</td></tr>
-<tr><td><a href="#Cube">Cube&lt;<i>type</i>&gt;, cube, cx_cube</a></td><td>&nbsp;</td><td>dense cube class ("3D matrix")</td></tr>
+<tr><td><a href="#Cube">Cube&lt;<i>type</i>&gt;, cube, cx_cube</a></td><td>&nbsp;</td><td>dense cube class (quasi third-order tensor, aka "3D matrix")</td></tr>
 <tr><td><a href="#field">field&lt;<i>object&nbsp;type</i>&gt;</a></td><td>&nbsp;</td><td>class for storing arbitrary objects in matrix-like or cube-like layouts</td></tr>
+<tr><td>&nbsp;</td><td>&nbsp;</td><td>&nbsp;</td></tr>
 <tr><td><a href="#SpMat">SpMat&lt;<i>type</i>&gt;, sp_mat, sp_cx_mat</a></td><td>&nbsp;</td><td>sparse matrix class</td></tr>
 <tr><td>&nbsp;</td><td>&nbsp;</td><td>&nbsp;</td></tr>
 <tr><td><a href="#operators">operators</a></td><td>&nbsp;</td><td><code><big>+</big>&nbsp; <big>&minus;</big>&nbsp; <big>*</big>&nbsp; %&nbsp; /&nbsp; ==&nbsp; !=&nbsp; &lt;=&nbsp; &gt;=&nbsp; &lt;&nbsp; &gt;&nbsp; &amp;&amp;&nbsp; ||</code></td></tr>
@@ -578,8 +579,6 @@ Conrad Sanderson and Ryan Curtin.
 <tr style="background-color: #F5F5F5;"><td><a href="#example_prog">example&nbsp;program</a></td><td>&nbsp;</td><td>short example program</td></tr>
 <tr><td><a href="#config_hpp">config.hpp</a></td><td>&nbsp;</td><td>configuration options</td></tr>
 <tr><td><a href="#changelog">API&nbsp;additions</a></td><td>&nbsp;</td><td>API stability and list of API additions</td></tr>
-<!--<tr><td><a href="#log_add">log_add</a></td><td>&nbsp;</td><td>TODO</td></tr>-->
-<!--<tr><td><a href="#catching_exceptions">catching exceptions</a></td><td>&nbsp;</td><td>TODO</td></tr>-->
 </tbody>
 </table>
 </ul>
@@ -760,6 +759,8 @@ Functions which use LAPACK (generally matrix decompositions) are only valid for
 <a name="constructors_mat"></a>
 <li>
 Constructors:
+<br>
+<br>
 <ul>
 <table>
 <tbody>
@@ -784,22 +785,27 @@ Constructors:
 <li>
 Matrix elements can be explicitly initialised during construction by specifying <i>fill_form</i>,
 which is one of:
+<br>
+<br>
 <ul>
 <table>
 <tbody>
-<tr><td><code>fill::zeros</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to 0</td></tr>
-<tr><td><code>fill::ones</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to 1</td></tr>
-<tr><td><code>fill::eye</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set the elements on the main diagonal to 1 and off-diagonal elements to 0</td></tr>
-<tr><td><code>fill::randu</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to random values from a uniform distribution in the [0,1] interval</td></tr>
-<tr><td><code>fill::randn</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to random values from a normal/Gaussian distribution with zero mean and unit variance</td></tr>
-<tr><td><code>fill::value(scalar)</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to specified scalar</td></tr>
 <tr><td><code>fill::none</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>do not initialise the elements &nbsp; (matrix may have garbage values)</td></tr>
+<tr><td><code>fill::zeros</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to 0 &nbsp; (default operation)</td></tr>
+<tr><td><code>fill::ones</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to 1</td></tr>
+<!-- <tr><td><code>fill::nan</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to NaN</td></tr> -->
+<!-- <tr><td><code>fill::pos_inf</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to +infinity</td></tr> -->
+<!-- <tr><td><code>fill::neg_inf</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to -infinity</td></tr> -->
+<tr><td><code>fill::value(scalar)</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to the specified scalar</td></tr>
+<tr><td><code>fill::eye</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set elements on the main diagonal to 1 and off-diagonal elements to 0</td></tr>
+<tr><td><code>fill::randu</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set elements to random values from a uniform distribution in the [0,1] interval</td></tr>
+<tr><td><code>fill::randn</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set elements to random values from a normal/Gaussian distribution with mean&thinsp;=&thinsp;0 and variance&thinsp;=&thinsp;1</td></tr>
 </tbody>
 </table>
 </ul>
 </li>
 <br>
-<li>Default element initialisation is <code>fill::zeros</code> (since Armadillo 10.5)</li>
+<li>If <i>fill_form</i> is not specified, <i>fill::zeros</i> is used by default (since Armadillo 10.5)</li>
 <br>
 <li>
 For the <i>mat(string)</i> constructor, the format is elements separated by spaces, and rows denoted by semicolons;
@@ -887,6 +893,16 @@ data is copied from auxiliary memory, where <i>ptr_aux_mem</i> is a pointer to t
 </ul>
 </li>
 <br>
+<li>
+Support for the <i>std::uint8_t</i> and <i>std::int8_t</i> element types can be enabled by defining both <code>ARMA_U8_TYPE</code> and <code>ARMA_S8_TYPE</code> before including the armadillo header:
+<ul>
+<pre>
+#define ARMA_U8_TYPE std::uint8_t
+#define ARMA_S8_TYPE  std::int8_t
+#include &lt;armadillo&gt;
+</pre>
+</ul>
+</li>
 <br>
 <li>
 Examples:
@@ -1154,6 +1170,8 @@ main exceptions are functions which require square matrices
 <br>
 <li>
 Constructors:
+<br>
+<br>
 <ul>
 <table>
 <tbody>
@@ -1426,6 +1444,8 @@ main exceptions are functions which require square matrices
 <br>
 <li>
 Constructors:
+<br>
+<br>
 <ul>
 <table>
 <tbody>
@@ -1552,11 +1572,11 @@ rowvec z = A.row(5); // extract a row vector
 <br><b>cx_cube</b>
 <ul>
 <li>
-Classes for cubes (quasi 3rd order tensors), also known as "3D matrices"
+Classes for cubes (quasi third-order tensors, aka "3D matrices")
 </li>
 <br>
 <li>
-Data is stored as a set of slices (matrices) stored contiguously within memory;
+Data is stored as an ordered set of slices (matrices) placed contiguously within memory;
 within each slice, elements are stored with column-major ordering (ie. column by column)
 </li>
 <br>
@@ -1704,6 +1724,8 @@ it is possible to use other types instead, eg. <i>fcube</i>
 <a name="constructors_cube"></a>
 <li>
 Constructors:
+<br>
+<br>
 <ul>
 <table>
 <tbody>
@@ -1722,21 +1744,26 @@ Constructors:
 <li>
 Cube elements can be explicitly initialised during construction by specifying <i>fill_form</i>,
 which is one of:
+<br>
+<br>
 <ul>
 <table>
 <tbody>
-<tr><td><code>fill::zeros</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to 0</td></tr>
-<tr><td><code>fill::ones</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to 1</td></tr>
-<tr><td><code>fill::randu</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to random values from a uniform distribution in the [0,1] interval</td></tr>
-<tr><td><code>fill::randn</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to random values from a normal/Gaussian distribution with zero mean and unit variance</td></tr>
-<tr><td><code>fill::value(scalar)</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to specified scalar</td></tr>
 <tr><td><code>fill::none</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>do not initialise the elements &nbsp; (cube may have garbage values)</td></tr>
+<tr><td><code>fill::zeros</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to 0 &nbsp; (default operation)</td></tr>
+<tr><td><code>fill::ones</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to 1</td></tr>
+<!-- <tr><td><code>fill::nan</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to NaN</td></tr> -->
+<!-- <tr><td><code>fill::pos_inf</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to +infinity</td></tr> -->
+<!-- <tr><td><code>fill::neg_inf</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to -infinity</td></tr> -->
+<tr><td><code>fill::value(scalar)</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set all elements to the specified scalar</td></tr>
+<tr><td><code>fill::randu</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set elements to random values from a uniform distribution in the [0,1] interval</td></tr>
+<tr><td><code>fill::randn</code></td><td>&nbsp;&mapsto;&nbsp;</td><td>set elements to random values from a normal/Gaussian distribution with mean&thinsp;=&thinsp;0 and variance&thinsp;=&thinsp;1</td></tr>
 </tbody>
 </table>
 </ul>
 </li>
 <br>
-<li>Default element initialisation is <code>fill::zeros</code> (since Armadillo 10.5)</li>
+<li>If <i>fill_form</i> is not specified, <i>fill::zeros</i> is used by default (since Armadillo 10.5)</li>
 <br>
 <li>
 Each instance of <i>cube</i> automatically allocates and releases internal memory.
@@ -1872,6 +1899,8 @@ Each element can have an arbitrary size (eg. in a field of matrices, each matrix
 <br>
 <li>
 Constructors, where <i>object_type</i> is another class, eg. <i>vec</i>, <i>mat</i>, <i>std::string</i>, etc:
+<br>
+<br>
 <ul>
 <table>
 <tbody>
@@ -1898,6 +1927,7 @@ mat A = randn(2,3);
 mat B = randn(4,5);

 field&lt;mat&gt; F(2,1);
+
 F(0,0) = A;
 F(1,0) = B; 

@@ -2072,6 +2102,8 @@ it is possible to use other types instead, eg. <i>sp_fmat</i>
 <a name="constructors_sp_mat"></a>
 <li>
 Constructors:
+<br>
+<br>
 <ul>
 <table>
 <tbody>
@@ -2109,6 +2141,8 @@ for small matrices use the <a href="#Mat">Mat</a> class, even if most of the ele
 <li>
 <a name="batch_constructors_sp_mat"></a>
 Batch insertion constructors:
+<br>
+<br>
 <ul>
 <li>form&nbsp;1: <code>sp_mat(<i>locations</i>, <i>values</i>, <i>sort_locations&thinsp;=&thinsp;true</i>)</code></li>
 <li>form&nbsp;2: <code>sp_mat(<i>locations</i>, <i>values</i>, <i>n_rows</i>, <i>n_cols</i>, <i>sort_locations&thinsp;=&thinsp;true</i>, <i>check_for_zeros&thinsp;=&thinsp;true</i>)</code></li>
@@ -2162,6 +2196,8 @@ If <i>check_for_zeros</i> is set to <i>false</i>, the <i>values</i> vector is as
 <br>
 <li>
 The following subset of operations &amp; functions is available for sparse matrices:
+<br>
+<br>
 <ul>
 <li>fundamental arithmetic <a href="#operators">operations</a> (such as addition and multiplication)</li>
 <li><a href="#submat">submatrix views</a>: most contiguous forms and the non-contiguous form of <i>X.cols(vector_of_column_indices)</i></li>
@@ -2211,10 +2247,6 @@ See also:
 <li><a href="#element_access">element access</a></li>
 <li><a href="#iterators_spmat">element iterators (sparse matrices)</a></li>
 <li><a href="#print">printing matrices</a></li>
-<!--
-<li><a href="#SpCol">SpCol class</a> (TODO: add to documentation)</li>
-<li><a href="#SpRow">SpRow class</a> (TODO: add to documentation)</li>
-->
 <li><a href="https://en.wikipedia.org/wiki/Sparse_matrix">Sparse Matrix in Wikipedia</a></li>
 <li><a href="#Mat">Mat class</a> (dense matrix)</li>
 </ul>
@@ -2941,6 +2973,7 @@ C.eye();
 <li>See also:
 <ul>
 <li><a href="#ones_member">.ones()</a></li>
+<li><a href="#fill">.fill()</a></li>
 <li><a href="#diag">.diag()</a></li>
 <li><a href="#diagmat">diagmat()</a></li>
 <li><a href="#diagvec">diagvec()</a></li>
@@ -3099,7 +3132,7 @@ See also:
 Member function of <i>Mat</i>, <i>Col</i>, <i>Row</i>, <i>Cube</i>, <i>field</i>
 </li>
 <br>
-<li>Sets the elements to a specified value</li>
+<li>Sets all elements to a specified value</li>
 <br>
 <li>The type of value must match the type of elements used by the container object (eg. for <i>mat</i> the type is <i>double</i>)
 </li>
@@ -3110,29 +3143,38 @@ Examples:
 <pre>
 mat A(5, 6);

-A.fill(123.0);   // or:  mat A(5, 6, fill::value(123.0));
+A.fill(123.0);
 </pre>
 </ul>
 </li>
 <br>
 <li>
-<b>Note:</b> to set all elements to zero during matrix construction, use the following more compact form:
+<b>Caveats:</b>
+<ul>
+<li>To initialise all elements during matrix construction, it is more efficient to use a <i><a href="#Mat">fill_form</a></i>:
 <ul>
 <pre>
 mat A(5, 6, fill::zeros);
+mat B(5, 6, fill::ones);
+mat C(5, 6, fill::value(123.0));
 </pre>
 </ul>
 </li>
+<li>If <i>fill_form</i> is not specified, <i>fill::zeros</i> is used by default (since Armadillo 10.5)</li>
+</ul>
+</li>
 <br>
 <li>
 See also:
 <ul>
 <li><a href="#imbue">.imbue()</a></li>
-<li><a href="#ones_member">.ones()</a></li>
 <li><a href="#zeros_member">.zeros()</a></li>
+<li><a href="#ones_member">.ones()</a></li>
+<li><a href="#eye_member">.eye()</a></li>
 <li><a href="#randu_randn_member">.randu() &amp; .randn()</a></li>
 <li><a href="#replace">.replace()</a></li>
 <li><a href="#constants">constants (pi, nan, inf, ...)</a></li>
+<li><a href="#Mat">matrix constructors</a></li>
 </ul>
 </li>
 <br>
@@ -3917,6 +3959,10 @@ Instances of <i>span(start,end)</i> can be replaced by <i>span::all</i> to indic
 </li>
 <br>
 <li>
+To distinguish <i>span(start,end)</i> from <i>std::span</i>, use the <i>arma::</i> prefix, ie. <i>arma::span(start,end)</i>
+</li>
+<br>
+<li>
 For functions requiring one or more vector of indices,
 eg. <i>X.submat(vector_of_row_indices,&nbsp;vector_of_column_indices)</i>,
 each vector of indices must be of type <i><a href="#Col">uvec</a></i>
@@ -4080,8 +4126,8 @@ Instances of <i>span(a,b)</i> can be replaced by:
 </li>
 <br>
 <li>
-An individual slice, accessed via <i>.slice()</i>, is an instance of the <i>Mat</i> class
-(a reference to a matrix is provided)
+A single slice, accessed via <i>.slice(slice_number)</i>, is an instance of the <i>Mat</i> class (a reference to a matrix is provided);
+<br>see also <i>.<a href="#col_row_as_mat">col_as_mat()</a></i> and <i>.<a href="#col_row_as_mat">row_as_mat()</a></i>
 </li>
 <br>
 <li>
@@ -5814,6 +5860,7 @@ Examples:
 <ul>
 <pre>
 mat X(4, 5, fill::randu);
+
 vec v = X.as_col();
 </pre>
 </ul>
@@ -5867,9 +5914,11 @@ Examples:
 <pre>
 cube Q(5, 4, 3, fill::randu);

-mat A = Q.col_as_mat(2);  // size of A: 5x3
+mat A = Q.slice(2);       // size of A: 5x4

-mat B = Q.row_as_mat(2);  // size of B: 3x4
+mat B = Q.col_as_mat(2);  // size of B: 5x3
+
+mat C = Q.row_as_mat(2);  // size of C: 3x4
 </pre>
 </ul>
 </li>
@@ -9732,10 +9781,6 @@ See also:
 <li><i>expmat_sym(B,A)</i> resets <i>B</i> and returns a bool set to <i>false</i> (exception is not thrown)</li>
 </ul>
 </li>
-<!--
-<br>
-<li><b>Caveat:</b> there is no explicit check whether <i>A</i> is symmetric/hermitian</li>
-->
 <br>
 <li><b>Caveat:</b> the matrix exponential operation is generally <b>not</b> the same as applying the <a href="#misc_fns">exp()</a> function to each element</li>
 <br>
@@ -10706,10 +10751,6 @@ See also:
 <li><i>logmat_sympd(B,A)</i> resets <i>B</i> and returns a bool set to <i>false</i> (exception is not thrown)</li>
 </ul>
 </li>
-<!--
-<br>
-<li><b>Caveat:</b> there is no explicit check whether <i>A</i> is symmetric/hermitian positive definite</li>
-->
 <br>
 <li><b>Caveat:</b> the matrix logarithm operation is generally <b>not</b> the same as applying the <a href="#misc_fns">log()</a> function to each element</li>
 <br>
@@ -11106,11 +11147,6 @@ See also:
 <tbody>
 <tr><td><b>pow( A, scalar )</b></td><td>&nbsp;&nbsp;&nbsp;</td><td>(form&nbsp;1)</td></tr>
 <tr><td><b>pow( A, B )</b></td><td>&nbsp;&nbsp;&nbsp;</td><td>(form&nbsp;2)</td></tr>
-<!--
-<tr><td><b>pow( M.each_col(), C )</b></td><td>&nbsp;&nbsp;&nbsp;</td><td>(form&nbsp;3)</td></tr>
-<tr><td><b>pow( M.each_row(), R )</b></td><td>&nbsp;&nbsp;&nbsp;</td><td>(form&nbsp;4)</td></tr>
-<tr><td><b>pow( Q.each_slice(), M )</b></td><td>&nbsp;&nbsp;&nbsp;</td><td>(form&nbsp;5)</td></tr>
-->
 </tbody>
 </table>
 <ul>
@@ -11120,17 +11156,6 @@ See also:
 <br>
 <li>form 2: raise each element in <i>A</i> to the power denoted by the corresponding element in <i>B</i>; sizes of <i>A</i> and <i>B</i> must be the same</li>
 <br>
-<!--
-<li>form 3: for each column vector of matrix <i>M</i>, raise each element to the power denoted by the corresponding element in column vector <i>C</i>;
-<br>the number of rows in <i>M</i> and <i>C</i> must be the same</li>
-<br>
-<li>form 4: for each row vector of matrix <i>M</i>, raise each element to the power denoted by the corresponding element in row vector <i>R</i>;
-<br>the number of columns in <i>M</i> and <i>R</i> must be the same</li>
-<br>
-<li>form 5: for each slice of cube <i>Q</i>, raise each element to the power denoted by the corresponding element in matrix <i>M</i>;
-<br>the number of rows and columns in <i>Q</i> and <i>M</i> must be the same</li>
-<br>
-->
 <li><b>Caveats</b>:
 <ul>
 <li>to raise all elements to the power 2, use <a href="#misc_fns">square()</a> instead</li>
@@ -11147,13 +11172,6 @@ mat B(5, 6, fill::randu);
 mat X = pow(A, 3.45);
 mat Y = pow(A, B);
 </pre>
-<!--
-   vec C(5, fill::randu);
-rowvec R(6, fill::randu);
-
-mat Z1 = pow(A.each_col(), C);
-mat Z2 = pow(A.each_row(), R);
-->
 </ul>
 </li>
 <br>
@@ -11162,10 +11180,6 @@ See also:
 <ul>
 <li><a href="#powmat">powmat()</a></li>
 <li><a href="#misc_fns">miscellaneous element-wise functions</a></li>
-<!--
-<li><a href="#each_colrow">.each_col() &amp; .each_row()</a></li>
-<li><a href="#each_slice">.each_slice()</a></li>
-->
 </ul>
 </li>
 <br>
@@ -12050,10 +12064,6 @@ See also:
 <li><i>sqrtmat_sympd(B,A)</i> resets <i>B</i> and returns a bool set to <i>false</i> (exception is not thrown)</li>
 </ul>
 </li>
-<!--
-<br>
-<li><b>Caveat:</b> there is no explicit check whether <i>A</i> is symmetric/hermitian positive definite</li>
-->
 <br>
 <li><b>Caveat:</b> the matrix square root operation is generally <b>not</b> the same as applying the <a href="#misc_fns">sqrt()</a> function to each element</li>
 <br>
@@ -13194,10 +13204,6 @@ the divide-and-conquer method provides slightly different results than the stand
 <li><i>eig_sym(eigval,eigvec,X)</i> resets <i>eigval</i> &amp; <i>eigvec</i> and returns a bool set to <i>false</i> (exception is not thrown)</li>
 </ul>
 </li>
-<!--
-<br>
-<li><b>Caveat:</b> there is no explicit check whether <i>X</i> is symmetric/hermitian</li>
-->
 <br>
 <li>
 Examples:
@@ -13575,10 +13581,6 @@ If <i>A</i> is not square sized, a <i>std::logic_error</i> exception is thrown
 <li><i>inv_sympd(B,rcond,A)</i> resets <i>B</i>, sets rcond to zero, and returns a bool set to <i>false</i> (exception is not thrown)</li>
 </ul>
 </li>
-<!--
-<br>
-<li><b>Caveat:</b> there is no explicit check whether <i>A</i> is symmetric/hermitian positive definite</li>
-->
 <br>
 <li>
 <b>Caveat:</b> 
@@ -14970,7 +14972,6 @@ See also:
 <ul>
 <li><a href="#spsolve_factoriser">spsolve_factoriser</a></li>
 <li><a href="#solve">solve()</a> - solve dense system of linear equations</li>
-<!-- <li><a href="http://crd-legacy.lbl.gov/~xiaoye/SuperLU/">SuperLU home page</a> -->
 <li><a href="https://portal.nersc.gov/project/sparse/superlu/">SuperLU home page</a>
 <li><a href="https://mathworld.wolfram.com/LinearSystemofEquations.html">linear system of equations in MathWorld</a></li>
 <li><a href="https://en.wikipedia.org/wiki/Linear_system_of_equations">system of linear equations in Wikipedia</a></li>
@@ -17891,7 +17892,6 @@ model.save("my_model.gmm");
    </td>
    <td style="vertical-align: top;">
      machine epsilon; approximately 2.2204e-16; difference between 1 and the next representable value
-      <!-- machine epsilon: the difference between 1 and the value least greater than 1 that is representable  (type and machine dependent) -->
    </td>
  </tr>
  <tr>
@@ -18436,7 +18436,7 @@ An instance of the class has the following member functions:
      </td>
      <td style="vertical-align: top;">
      return the number of seconds since the last call to <code>.tic()</code>,
-      with the returned number of seconds reduced by any freeze/unfreeze durations
+      with the number of seconds reduced by any freeze/unfreeze durations
      </td>
    </tr>
    <tr>
@@ -18617,33 +18617,6 @@ See also:
 <br>
 </ul>

-<!--
-<div class="pagebreak"></div><div class="noprint"><hr class="greyline"><br></div>
-<a name="log_add"></a>
-<b>log_add(log_a, log_b)</b>
-<ul>
-<li>
-Safe replacement for log(exp(log_a) + exp(log_b))
-</li>
-<br>
-<li>
-Usage:
-<ul>
-<li>
-<i>scalar_type</i> log_c = log_add(log_a, log_b)
-</li>
-<li>
-<i>scalar_type</i> is either <i>float</i> or <i>double</i>
-</li>
-<li>
-log_a, log_b and log_c must have the same type
-</li>
-</ul>
-</li>
-</ul>
-<br>
-->
-
 <div class="pagebreak"></div><div class="noprint"><hr class="greyline"><br></div>
 <a name="uword"></a>
 <b>uword</b>, <b>sword</b>
@@ -18819,7 +18792,6 @@ fp16 val = X(2,3);
 <li><a href="#Mat">hmat</a> matrix type
 <li><a href="#Col">hvec</a> vector type
 <li><a href="https://en.cppreference.com/w/cpp/types/floating-point.html">std::float16_t</a> in cppreference.com</li>
-<!-- <li><a href="https://en.cppreference.com/w/cpp/header/stdfloat.html">std::float16_t</a> in cppreference.com</li> -->
 <li><a href="https://en.wikipedia.org/wiki/Half-precision_floating-point_format">half-precision floating point format in Wikipedia</a></li>
 <li><a href="https://en.wikipedia.org/wiki/AVX-512">AVX-512 extensions in Wikipedia</a></li>
 <!-- <li><a href="https://gcc.gnu.org/onlinedocs/gcc/Half-Precision.html">gcc half-precision documentation</a></li> -->
@@ -20691,60 +20663,6 @@ See also:
 <br>
 </ul>

-<!--
-<div class="pagebreak"></div><div class="noprint"><hr class="greyline"><br></div>
-<a name="catching_exceptions"></a>
-<br>
-<b>how to catch std::runtime_error exceptions</b>
-<br>
-<br>
-<ul>
-<li>
-If a function such as <a href="#inv">inv()</a> fails to find a solution,
-an error message is printed and a <i>std::runtime_error</i> exception is thrown.
-If the exception is not caught, the program typically terminates.
-Below is an example of how to catch exceptions:
-<ul>
-<pre>
-#include &lt;iostream&gt;
-#include &lt;armadillo&gt;
-
-using namespace std;
-using namespace arma;
-
-int main(int argc, char** argv)
-  {
-  // create a non-invertible matrix
-  mat A(5, 5, fill::zeros);
-  
-  mat B;
-  
-  try
-    {
-    B = inv(A);
-    }
-  catch (std::runtime_error&amp; x)
-    {
-    cout &lt;&lt; "caught an exception" &lt;&lt; endl;
-    }
-  
-  return 0;
-  }
-</pre>
-</ul>
-<li>
-See also:
-<ul>
-<li><a href="#logging">logging of warnings and errors</a></li>
-<li><a href="https://cplusplus.com/doc/tutorial/exceptions/">tutorial on exceptions</a></li>
-<li><a href="https://cplusplus.com/reference/stdexcept/runtime_error/">std::runtime_error</a></li>
-</ul>
-</li>
-<br>
-</ul>
-<br>
-->
-
 <div class="pagebreak"></div><div class="noprint"><hr class="greyline"><br></div>
 <a name="api_additions"></a>
 <a name="changelog"></a>
@@ -20792,19 +20710,6 @@ and may be changed or removed without notice.
 </ul>
 </li>

-<!--
-<br>
-<li>
-<a name="deprecated"></a>
-List of deprecated functionality; this functionality will be <b>removed</b> in version A.B:
-<ul>
-<li>
-...
-</li>
-</ul>
-</li>
-->
-
 <br>
 <br>
 <li>
@@ -20821,6 +20726,7 @@ List of additions and changes for each version:
 <li>added <a href="#rande">rande()</a> for generating matrices with elements from exponential distributions</li>
 <li>shift() has been deprecated in favour of <a href="#circshift">circshift()</a>, for consistency with Matlab/Octave</li>
 <li>reworked detection of aliasing, leading to more efficient compiled code</li>
+<li>faster handling of submatrices with one row</li>
 </ul>
 </li>
 <br>
@@ -21929,6 +21835,7 @@ use <i>my_function(&nbsp;mat(A+B)&nbsp;)</i>.
 <br>
 </ul>

+
 <!-- END CONTENT -->


@@ -244,9 +244,9 @@ BaseCube<elem_type,derived>::is_zero(const typename get_pod_type<elem_type>::res
  
  typedef typename get_pod_type<elem_type>::result T;
  
-  arma_conform_check( (tol < T(0)), "is_zero(): parameter 'tol' must be >= 0" );
+  arma_conform_check( ((tol >= T(0)) == false), "is_zero(): parameter 'tol' must be >= 0" );
  
-  if(ProxyCube<derived>::use_at || is_Cube<typename ProxyCube<derived>::stored_type>::value)
+  if(is_Cube<typename ProxyCube<derived>::stored_type>::value || ProxyCube<derived>::use_at)
    {
    const unwrap_cube<derived> U( (*this).get_ref() );
    
@@ -263,22 +263,52 @@ BaseCube<elem_type,derived>::is_zero(const typename get_pod_type<elem_type>::res
  
  if(is_cx<elem_type>::yes)
    {
-    for(uword i=0; i<n_elem; ++i)
+    if(tol == T(0))
      {
-      const elem_type val = Pea[i];
-      
-      const T val_real = access::tmp_real(val);
-      const T val_imag = access::tmp_imag(val);
-      
-      if(eop_aux::arma_abs(val_real) > tol)  { return false; }
-      if(eop_aux::arma_abs(val_imag) > tol)  { return false; }
+      for(uword i=0; i < n_elem; ++i)
+        {
+        const elem_type val = Pea[i];
+        
+        const T val_real = access::tmp_real(val);
+        const T val_imag = access::tmp_imag(val);
+        
+        if(eop_aux::arma_abs(val_real) != T(0))  { return false; }
+        if(eop_aux::arma_abs(val_imag) != T(0))  { return false; }
+        }
+      }
+    else
+      {
+      for(uword i=0; i < n_elem; ++i)
+        {
+        const elem_type val = Pea[i];
+        
+        const T val_real = access::tmp_real(val);
+        const T val_imag = access::tmp_imag(val);
+        
+        if( (eop_aux::arma_abs(val_real) <= tol) == false )  { return false; }
+        if( (eop_aux::arma_abs(val_imag) <= tol) == false )  { return false; }
+        }
      }
    }
  else  // not complex
    {
-    for(uword i=0; i < n_elem; ++i)
+    if(tol == T(0))
      {
-      if(eop_aux::arma_abs(Pea[i]) > tol)  { return false; }
+      for(uword i=0; i < n_elem; ++i)
+        {
+        const elem_type val = Pea[i];
+        
+        if(val != elem_type(0))  { return false; }
+        }
+      }
+    else
+      {
+      for(uword i=0; i < n_elem; ++i)
+        {
+        const elem_type val = Pea[i];
+        
+        if( (eop_aux::arma_abs(val) <= tol) == false )  { return false; }
+        }
      }
    }
  
@@ -352,7 +352,7 @@ Base<elem_type,derived>::is_symmetric(const typename get_pod_type<elem_type>::re
  
  if(tol == T(0))  { return (*this).is_symmetric(); }
  
-  arma_conform_check( (tol < T(0)), "is_symmetric(): parameter 'tol' must be >= 0" );
+  arma_conform_check( ((tol >= T(0)) == false), "is_symmetric(): parameter 'tol' must be > 0" );
  
  const quasi_unwrap<derived> U( (*this).get_ref() );
  
@@ -365,8 +365,12 @@ Base<elem_type,derived>::is_symmetric(const typename get_pod_type<elem_type>::re
  
  if(norm_A == T(0))  { return true; }
  
+  if(arma_isnan(norm_A))  { return false; }
+  
  const T norm_A_Ast = as_scalar( arma::max(sum(abs(A - A.st()), 1), 0) );
  
+  if(arma_isnan(norm_A_Ast))  { return false; }
+  
  return ( (norm_A_Ast / norm_A) <= tol );
  }

@@ -435,7 +439,7 @@ Base<elem_type,derived>::is_hermitian(const typename get_pod_type<elem_type>::re
  
  if(tol == T(0))  { return (*this).is_hermitian(); }
  
-  arma_conform_check( (tol < T(0)), "is_hermitian(): parameter 'tol' must be >= 0" );
+  arma_conform_check( ((tol >= T(0)) == false), "is_hermitian(): parameter 'tol' must be > 0" );
  
  const quasi_unwrap<derived> U( (*this).get_ref() );
  
@@ -448,8 +452,12 @@ Base<elem_type,derived>::is_hermitian(const typename get_pod_type<elem_type>::re
  
  if(norm_A == T(0))  { return true; }
  
+  if(arma_isnan(norm_A))  { return false; }
+  
  const T norm_A_At = as_scalar( arma::max(sum(abs(A - A.t()), 1), 0) );
  
+  if(arma_isnan(norm_A_At))  { return false; }
+  
  return ( (norm_A_At / norm_A) <= tol );
  }

@@ -464,9 +472,9 @@ Base<elem_type,derived>::is_zero(const typename get_pod_type<elem_type>::result
  
  typedef typename get_pod_type<elem_type>::result T;
  
-  arma_conform_check( (tol < T(0)), "is_zero(): parameter 'tol' must be >= 0" );
+  arma_conform_check( ((tol >= T(0)) == false), "is_zero(): parameter 'tol' must be >= 0" );
  
-  if(Proxy<derived>::use_at || is_Mat<typename Proxy<derived>::stored_type>::value)
+  if( (quasi_unwrap<derived>::has_orig_mem) || (is_Mat<typename Proxy<derived>::stored_type>::value) || (Proxy<derived>::use_at) )
    {
    const quasi_unwrap<derived> U( (*this).get_ref() );
    
@@ -483,22 +491,52 @@ Base<elem_type,derived>::is_zero(const typename get_pod_type<elem_type>::result
  
  if(is_cx<elem_type>::yes)
    {
-    for(uword i=0; i<n_elem; ++i)
+    if(tol == T(0))
      {
-      const elem_type val = Pea[i];
-      
-      const T val_real = access::tmp_real(val);
-      const T val_imag = access::tmp_imag(val);
-      
-      if(eop_aux::arma_abs(val_real) > tol)  { return false; }
-      if(eop_aux::arma_abs(val_imag) > tol)  { return false; }
+      for(uword i=0; i < n_elem; ++i)
+        {
+        const elem_type val = Pea[i];
+        
+        const T val_real = access::tmp_real(val);
+        const T val_imag = access::tmp_imag(val);
+        
+        if(eop_aux::arma_abs(val_real) != T(0))  { return false; }
+        if(eop_aux::arma_abs(val_imag) != T(0))  { return false; }
+        }
+      }
+    else
+      {
+      for(uword i=0; i < n_elem; ++i)
+        {
+        const elem_type val = Pea[i];
+        
+        const T val_real = access::tmp_real(val);
+        const T val_imag = access::tmp_imag(val);
+        
+        if( (eop_aux::arma_abs(val_real) <= tol) == false )  { return false; }
+        if( (eop_aux::arma_abs(val_imag) <= tol) == false )  { return false; }
+        }
      }
    }
  else  // not complex
    {
-    for(uword i=0; i<n_elem; ++i)
+    if(tol == T(0))
      {
-      if(eop_aux::arma_abs(Pea[i]) > tol)  { return false; }
+      for(uword i=0; i < n_elem; ++i)
+        {
+        const elem_type val = Pea[i];
+        
+        if(val != elem_type(0))  { return false; }
+        }
+      }
+    else
+      {
+      for(uword i=0; i < n_elem; ++i)
+        {
+        const elem_type val = Pea[i];
+        
+        if( (eop_aux::arma_abs(val) <= tol) == false )  { return false; }
+        }
      }
    }
  
@@ -897,6 +935,8 @@ Base_extra_yes<elem_type,derived>::is_sympd() const
  // default value for tol
  const T tol = T(100) * std::numeric_limits<T>::epsilon() * norm(X, "fro");
  
+  if(arma_isnan(tol))  { return false; }
+  
  if(X.is_hermitian(tol) == false)  { return false; }
  
  if(X.is_empty())  { return false; }
@@ -917,7 +957,7 @@ Base_extra_yes<elem_type,derived>::is_sympd(typename get_pod_type<elem_type>::re
  
  typedef typename get_pod_type<elem_type>::result T;
  
-  arma_conform_check( (tol < T(0)), "is_sympd(): parameter 'tol' must be >= 0" );
+  arma_conform_check( ((tol >= T(0)) == false), "is_sympd(): parameter 'tol' must be > 0" );
  
  Mat<elem_type> X = static_cast<const derived&>(*this);
  
@@ -1344,6 +1344,10 @@ Col<eT>::fixed<fixed_n_elem>::fixed(const fill::fill_class<fill_type>&)
  if(is_same_type<fill_type, fill::fill_eye  >::yes)  { Mat<eT>::eye();   }
  if(is_same_type<fill_type, fill::fill_randu>::yes)  { Mat<eT>::randu(); }
  if(is_same_type<fill_type, fill::fill_randn>::yes)  { Mat<eT>::randn(); }
+  
+  if(is_same_type<fill_type, fill::fill_nan    >::yes)  { (*this).fill( priv::Datum_helper::nan    <eT>() ); }
+  if(is_same_type<fill_type, fill::fill_pos_inf>::yes)  { (*this).fill( priv::Datum_helper::pos_inf<eT>() ); }
+  if(is_same_type<fill_type, fill::fill_neg_inf>::yes)  { (*this).fill( priv::Datum_helper::neg_inf<eT>() ); }
  }


@@ -360,6 +360,9 @@ class Cube : public BaseCube< eT, Cube<eT> >
  
  inline Cube& fill(const eT val);
  
+  template<typename fill_type>
+  inline Cube& fill(const fill::fill_class<fill_type>& f);
+  
  inline Cube& zeros();
  inline Cube& zeros(const uword new_n_rows, const uword new_n_cols, const uword new_n_slices);
  inline Cube& zeros(const SizeCube& s);
@@ -52,7 +52,7 @@ Cube<eT>::Cube()
  , n_elem(0)
  , n_alloc(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  }
@@ -172,7 +172,7 @@ Cube<eT>::Cube(const SizeCube& s, const arma_initmode_indicator<do_zeros>&)
 template<typename eT>
 template<typename fill_type>
 inline
-Cube<eT>::Cube(const uword in_n_rows, const uword in_n_cols, const uword in_n_slices, const fill::fill_class<fill_type>&)
+Cube<eT>::Cube(const uword in_n_rows, const uword in_n_cols, const uword in_n_slices, const fill::fill_class<fill_type>& f)
  : n_rows(in_n_rows)
  , n_cols(in_n_cols)
  , n_elem_slice(in_n_rows*in_n_cols)
@@ -186,12 +186,7 @@ Cube<eT>::Cube(const uword in_n_rows, const uword in_n_cols, const uword in_n_sl
  
  init_cold();
  
-  if(is_same_type<fill_type, fill::fill_zeros>::yes)  { (*this).zeros(); }
-  if(is_same_type<fill_type, fill::fill_ones >::yes)  { (*this).ones();  }
-  if(is_same_type<fill_type, fill::fill_randu>::yes)  { (*this).randu(); }
-  if(is_same_type<fill_type, fill::fill_randn>::yes)  { (*this).randn(); }
-  
-  arma_static_check( (is_same_type<fill_type, fill::fill_eye>::yes), "Cube::Cube(): unsupported fill type" );
+  (*this).fill(f);
  }


@@ -199,7 +194,7 @@ Cube<eT>::Cube(const uword in_n_rows, const uword in_n_cols, const uword in_n_sl
 template<typename eT>
 template<typename fill_type>
 inline
-Cube<eT>::Cube(const SizeCube& s, const fill::fill_class<fill_type>&)
+Cube<eT>::Cube(const SizeCube& s, const fill::fill_class<fill_type>& f)
  : n_rows(s.n_rows)
  , n_cols(s.n_cols)
  , n_elem_slice(s.n_rows*s.n_cols)
@@ -213,12 +208,7 @@ Cube<eT>::Cube(const SizeCube& s, const fill::fill_class<fill_type>&)
  
  init_cold();
  
-  if(is_same_type<fill_type, fill::fill_zeros>::yes)  { (*this).zeros(); }
-  if(is_same_type<fill_type, fill::fill_ones >::yes)  { (*this).ones();  }
-  if(is_same_type<fill_type, fill::fill_randu>::yes)  { (*this).randu(); }
-  if(is_same_type<fill_type, fill::fill_randn>::yes)  { (*this).randn(); }
-  
-  arma_static_check( (is_same_type<fill_type, fill::fill_eye>::yes), "Cube::Cube(): unsupported fill type" );
+  (*this).fill(f);
  }


@@ -934,7 +924,7 @@ Cube<eT>::Cube
  , n_elem(0)
  , n_alloc(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -1064,7 +1054,7 @@ Cube<eT>::Cube(const subview_cube_slices<eT,T1>& X)
  , n_elem(0)
  , n_alloc(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -2751,7 +2741,7 @@ Cube<eT>::Cube(const OpCube<T1, op_type>& X)
  , n_elem(0)
  , n_alloc(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);

@@ -3048,7 +3038,7 @@ Cube<eT>::Cube(const mtOpCube<eT, T1, op_type>& X)
  , n_elem(0)
  , n_alloc(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -3144,7 +3134,7 @@ Cube<eT>::Cube(const GlueCube<T1, T2, glue_type>& X)
  , n_elem(0)
  , n_alloc(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -3401,7 +3391,7 @@ Cube<eT>::Cube(const mtGlueCube<eT, T1, T2, glue_type>& X)
  , n_elem(0)
  , n_alloc(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -3887,7 +3877,7 @@ arma_inline
 eT*
 Cube<eT>::slice_memptr(const uword uslice)
  {
-  return const_cast<eT*>( &mem[ uslice*n_elem_slice ] );
+  return access::rwp( mem + (uslice*n_elem_slice) );
  }


@@ -3898,7 +3888,7 @@ arma_inline
 const eT*
 Cube<eT>::slice_memptr(const uword uslice) const
  {
-  return &mem[ uslice*n_elem_slice ];
+  return mem + (uslice*n_elem_slice);
  }


@@ -3909,7 +3899,7 @@ arma_inline
 eT*
 Cube<eT>::slice_colptr(const uword uslice, const uword col)
  {
-  return const_cast<eT*>( &mem[ uslice*n_elem_slice + col*n_rows] );
+  return access::rwp( mem + (uslice*n_elem_slice + col*n_rows) );
  }


@@ -3920,7 +3910,7 @@ arma_inline
 const eT*
 Cube<eT>::slice_colptr(const uword uslice, const uword col) const
  {
-  return &mem[ uslice*n_elem_slice + col*n_rows ];
+  return mem + (uslice*n_elem_slice + col*n_rows);
  }


@@ -4197,12 +4187,12 @@ Cube<eT>::clamp(const eT min_val, const eT max_val)
  
  if(is_cx<eT>::no)
    {
-    arma_conform_check( (access::tmp_real(min_val) > access::tmp_real(max_val)), "Cube::clamp(): min_val must be less than max_val" );
+    arma_conform_check( ((access::tmp_real(min_val) <= access::tmp_real(max_val)) == false), "Cube::clamp(): min_val must be less than max_val" );
    }
  else
    {
-    arma_conform_check( (access::tmp_real(min_val) > access::tmp_real(max_val)), "Cube::clamp(): real(min_val) must be less than real(max_val)" );
-    arma_conform_check( (access::tmp_imag(min_val) > access::tmp_imag(max_val)), "Cube::clamp(): imag(min_val) must be less than imag(max_val)" );
+    arma_conform_check( ((access::tmp_real(min_val) <= access::tmp_real(max_val)) == false), "Cube::clamp(): real(min_val) must be less than real(max_val)" );
+    arma_conform_check( ((access::tmp_imag(min_val) <= access::tmp_imag(max_val)) == false), "Cube::clamp(): imag(min_val) must be less than imag(max_val)" );
    }
  
  arrayops::clamp(memptr(), n_elem, min_val, max_val);
@@ -4227,6 +4217,30 @@ Cube<eT>::fill(const eT val)



+template<typename eT>
+template<typename fill_type>
+inline
+Cube<eT>&
+Cube<eT>::fill(const fill::fill_class<fill_type>&)
+  {
+  arma_debug_sigprint();
+  
+  arma_static_check( (is_same_type<fill_type, fill::fill_eye>::yes), "Cube::fill(): unsupported fill type" );
+  
+  if(is_same_type<fill_type, fill::fill_zeros>::yes)  { (*this).zeros(); }
+  if(is_same_type<fill_type, fill::fill_ones >::yes)  { (*this).ones();  }
+  if(is_same_type<fill_type, fill::fill_randu>::yes)  { (*this).randu(); }
+  if(is_same_type<fill_type, fill::fill_randn>::yes)  { (*this).randn(); }
+  
+  if(is_same_type<fill_type, fill::fill_nan    >::yes)  { (*this).fill( priv::Datum_helper::nan    <eT>() ); }
+  if(is_same_type<fill_type, fill::fill_pos_inf>::yes)  { (*this).fill( priv::Datum_helper::pos_inf<eT>() ); }
+  if(is_same_type<fill_type, fill::fill_neg_inf>::yes)  { (*this).fill( priv::Datum_helper::neg_inf<eT>() ); }
+  
+  return *this;
+  }
+
+
+
 template<typename eT>
 inline
 Cube<eT>&
@@ -5458,18 +5472,13 @@ template<typename eT>
 template<uword fixed_n_rows, uword fixed_n_cols, uword fixed_n_slices>
 template<typename fill_type>
 inline
-Cube<eT>::fixed<fixed_n_rows, fixed_n_cols, fixed_n_slices>::fixed(const fill::fill_class<fill_type>&)
+Cube<eT>::fixed<fixed_n_rows, fixed_n_cols, fixed_n_slices>::fixed(const fill::fill_class<fill_type>& f)
  {
  arma_debug_sigprint_this(this);
  
  mem_setup();
  
-  if(is_same_type<fill_type, fill::fill_zeros>::yes)  { Cube<eT>::zeros(); }
-  if(is_same_type<fill_type, fill::fill_ones >::yes)  { Cube<eT>::ones();  }
-  if(is_same_type<fill_type, fill::fill_randu>::yes)  { Cube<eT>::randu(); }
-  if(is_same_type<fill_type, fill::fill_randn>::yes)  { Cube<eT>::randn(); }
-  
-  arma_static_check( (is_same_type<fill_type, fill::fill_eye>::yes), "Cube::fixed::fixed(): unsupported fill type" );
+  (*this).fill(f);
  }


@@ -255,7 +255,7 @@ Mat<eT>::Mat(const arma_vec_indicator&, const uhword in_vec_state)
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  }
@@ -456,7 +456,7 @@ Mat<eT>::Mat(const char* text)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -490,7 +490,7 @@ Mat<eT>::Mat(const std::string& text)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -678,7 +678,7 @@ Mat<eT>::Mat(const std::initializer_list<eT>& list)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -710,7 +710,7 @@ Mat<eT>::Mat(const std::initializer_list< std::initializer_list<eT> >& list)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -877,7 +877,7 @@ Mat<eT>::Mat(const Mat<eT>& in_mat, const arma_vec_indicator&, const uhword in_v
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint(arma_str::format("this: %x; in_mat: %x") % this % &in_mat);
  
@@ -1512,7 +1512,7 @@ Mat<eT>::Mat(const BaseCube<eT,T1>& X, const arma_vec_indicator&, const uhword i
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -1531,7 +1531,7 @@ Mat<eT>::Mat(const BaseCube<eT,T1>& X)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -1978,7 +1978,7 @@ Mat<eT>::Mat(const Base<typename Mat<eT>::pod_type,T1>& A, const Base<typename M
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -1998,7 +1998,7 @@ Mat<eT>::Mat(const Base<typename Mat<eT>::pod_type,T1>& A, const Base<typename M
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -2043,7 +2043,7 @@ Mat<eT>::Mat(const subview<eT>& X, const arma_vec_indicator&, const uhword in_ve
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -2266,7 +2266,7 @@ Mat<eT>::Mat(const subview_cube<eT>& x, const arma_vec_indicator&, const uhword
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -2285,7 +2285,7 @@ Mat<eT>::Mat(const subview_cube<eT>& x)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -2395,7 +2395,7 @@ Mat<eT>::Mat(const diagview<eT>& X, const arma_vec_indicator&, const uhword in_v
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -2540,7 +2540,7 @@ Mat<eT>::Mat(const subview_elem1<eT,T1>& X, const arma_vec_indicator&, const uhw
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -2559,7 +2559,7 @@ Mat<eT>::Mat(const subview_elem1<eT,T1>& X)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -2668,7 +2668,7 @@ Mat<eT>::Mat(const subview_elem2<eT,T1,T2>& X, const arma_vec_indicator&, const
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -2687,7 +2687,7 @@ Mat<eT>::Mat(const subview_elem2<eT,T1,T2>& X)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -2796,7 +2796,7 @@ Mat<eT>::Mat(const SpBase<eT, T1>& m, const arma_vec_indicator&, const uhword in
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -2815,7 +2815,7 @@ Mat<eT>::Mat(const SpBase<eT, T1>& m)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -2876,6 +2876,8 @@ Mat<eT>::operator+=(const SpBase<eT, T1>& m)
  
  arma_conform_assert_same_size(n_rows, n_cols, p.get_n_rows(), p.get_n_cols(), "addition");
  
+  if(p.get_n_nonzero() == 0)  { return *this; }
+  
  typename SpProxy<T1>::const_iterator_type it     = p.begin();
  typename SpProxy<T1>::const_iterator_type it_end = p.end();
  
@@ -2898,6 +2900,8 @@ Mat<eT>::operator-=(const SpBase<eT, T1>& m)
  
  arma_conform_assert_same_size(n_rows, n_cols, p.get_n_rows(), p.get_n_cols(), "subtraction");
  
+  if(p.get_n_nonzero() == 0)  { return *this; }
+  
  typename SpProxy<T1>::const_iterator_type it     = p.begin();
  typename SpProxy<T1>::const_iterator_type it_end = p.end();
  
@@ -2916,9 +2920,9 @@ Mat<eT>::operator*=(const SpBase<eT, T1>& m)
  {
  arma_debug_sigprint();
  
-  Mat<eT> z = (*this) * m.get_ref();
+  Mat<eT> tmp = (*this) * m.get_ref();
  
-  steal_mem(z);
+  steal_mem(tmp);
  
  return *this;
  }
@@ -2999,7 +3003,7 @@ Mat<eT>::Mat(const SpSubview<eT>& X, const arma_vec_indicator&, const uhword in_
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -3017,7 +3021,7 @@ Mat<eT>::Mat(const SpSubview<eT>& X)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -3200,7 +3204,7 @@ Mat<eT>::Mat(const spdiagview<eT>& X, const arma_vec_indicator&, const uhword in
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -5128,7 +5132,7 @@ Mat<eT>::Mat(const Gen<T1, gen_type>& X, const arma_vec_indicator&, const uhword
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -5278,7 +5282,7 @@ Mat<eT>::Mat(const Op<T1, op_type>& X, const arma_vec_indicator&, const uhword i
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -5300,7 +5304,7 @@ Mat<eT>::Mat(const Op<T1, op_type>& X)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -5429,7 +5433,7 @@ Mat<eT>::Mat(const eOp<T1, eop_type>& X, const arma_vec_indicator&, const uhword
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -5657,7 +5661,7 @@ Mat<eT>::Mat(const mtOp<eT, T1, op_type>& X, const arma_vec_indicator&, const uh
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -5676,7 +5680,7 @@ Mat<eT>::Mat(const mtOp<eT, T1, op_type>& X)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -5785,7 +5789,7 @@ Mat<eT>::Mat(const CubeToMatOp<T1, op_type>& X, const arma_vec_indicator&, const
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -5806,7 +5810,7 @@ Mat<eT>::Mat(const CubeToMatOp<T1, op_type>& X)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -5929,7 +5933,7 @@ Mat<eT>::Mat(const SpToDOp<T1, op_type>& X, const arma_vec_indicator&, const uhw
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -5950,7 +5954,7 @@ Mat<eT>::Mat(const SpToDOp<T1, op_type>& X)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -6079,7 +6083,7 @@ Mat<eT>::Mat(const mtSpReduceOp<eT, T1, op_type>& X, const arma_vec_indicator&,
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -6098,7 +6102,7 @@ Mat<eT>::Mat(const mtSpReduceOp<eT, T1, op_type>& X)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -6207,7 +6211,7 @@ Mat<eT>::Mat(const Glue<T1, T2, glue_type>& X, const arma_vec_indicator&, const
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -6230,7 +6234,7 @@ Mat<eT>::Mat(const Glue<T1, T2, glue_type>& X)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -6396,7 +6400,7 @@ Mat<eT>::Mat(const eGlue<T1, T2, eglue_type>& X, const arma_vec_indicator&, cons
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -6603,7 +6607,7 @@ Mat<eT>::Mat(const mtGlue<eT, T1, T2, glue_type>& X, const arma_vec_indicator&,
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -6622,7 +6626,7 @@ Mat<eT>::Mat(const mtGlue<eT, T1, T2, glue_type>& X)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -6733,7 +6737,7 @@ Mat<eT>::Mat(const SpToDGlue<T1, T2, glue_type>& X, const arma_vec_indicator&, c
  , n_alloc(0)
  , vec_state(in_vec_state)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -6755,7 +6759,7 @@ Mat<eT>::Mat(const SpToDGlue<T1, T2, glue_type>& X)
  , n_alloc(0)
  , vec_state(0)
  , mem_state(0)
-  , mem()
+  , mem(nullptr)
  {
  arma_debug_sigprint_this(this);
  
@@ -7475,7 +7479,7 @@ arma_inline
 eT*
 Mat<eT>::colptr(const uword in_col)
  {
-  return & access::rw(mem[in_col*n_rows]);
+  return access::rwp( mem + (in_col*n_rows) );
  }


@@ -7486,7 +7490,7 @@ arma_inline
 const eT*
 Mat<eT>::colptr(const uword in_col) const
  {
-  return & mem[in_col*n_rows];
+  return mem + (in_col*n_rows);
  }


@@ -7881,12 +7885,12 @@ Mat<eT>::clamp(const eT min_val, const eT max_val)
  
  if(is_cx<eT>::no)
    {
-    arma_conform_check( (access::tmp_real(min_val) > access::tmp_real(max_val)), "Mat::clamp(): min_val must be less than max_val" );
+    arma_conform_check( ((access::tmp_real(min_val) <= access::tmp_real(max_val)) == false), "Mat::clamp(): min_val must be less than max_val" );
    }
  else
    {
-    arma_conform_check( (access::tmp_real(min_val) > access::tmp_real(max_val)), "Mat::clamp(): real(min_val) must be less than real(max_val)" );
-    arma_conform_check( (access::tmp_imag(min_val) > access::tmp_imag(max_val)), "Mat::clamp(): imag(min_val) must be less than imag(max_val)" );
+    arma_conform_check( ((access::tmp_real(min_val) <= access::tmp_real(max_val)) == false), "Mat::clamp(): real(min_val) must be less than real(max_val)" );
+    arma_conform_check( ((access::tmp_imag(min_val) <= access::tmp_imag(max_val)) == false), "Mat::clamp(): imag(min_val) must be less than imag(max_val)" );
    }
  
  arrayops::clamp(memptr(), n_elem, min_val, max_val);
@@ -7926,6 +7930,10 @@ Mat<eT>::fill(const fill::fill_class<fill_type>&)
  if(is_same_type<fill_type, fill::fill_randu>::yes)  { (*this).randu(); }
  if(is_same_type<fill_type, fill::fill_randn>::yes)  { (*this).randn(); }
  
+  if(is_same_type<fill_type, fill::fill_nan    >::yes)  { (*this).fill( priv::Datum_helper::nan    <eT>() ); }
+  if(is_same_type<fill_type, fill::fill_pos_inf>::yes)  { (*this).fill( priv::Datum_helper::pos_inf<eT>() ); }
+  if(is_same_type<fill_type, fill::fill_neg_inf>::yes)  { (*this).fill( priv::Datum_helper::neg_inf<eT>() ); }
+  
  return *this;
  }

@@ -10099,6 +10107,10 @@ Mat<eT>::fixed<fixed_n_rows, fixed_n_cols>::fixed(const fill::fill_class<fill_ty
  if(is_same_type<fill_type, fill::fill_eye  >::yes)  { Mat<eT>::eye();   }
  if(is_same_type<fill_type, fill::fill_randu>::yes)  { Mat<eT>::randu(); }
  if(is_same_type<fill_type, fill::fill_randn>::yes)  { Mat<eT>::randn(); }
+  
+  if(is_same_type<fill_type, fill::fill_nan    >::yes)  { (*this).fill( priv::Datum_helper::nan    <eT>() ); }
+  if(is_same_type<fill_type, fill::fill_pos_inf>::yes)  { (*this).fill( priv::Datum_helper::pos_inf<eT>() ); }
+  if(is_same_type<fill_type, fill::fill_neg_inf>::yes)  { (*this).fill( priv::Datum_helper::neg_inf<eT>() ); }
  }


@@ -10533,7 +10545,7 @@ Mat<eT>::fixed<fixed_n_rows, fixed_n_cols>::colptr(const uword in_col)
  {
  eT* mem_actual = (use_extra) ? mem_local_extra : mem_local;
  
-  return & access::rw(mem_actual[in_col*fixed_n_rows]);
+  return access::rwp( mem_actual + (in_col*fixed_n_rows) );
  }


@@ -10546,7 +10558,7 @@ Mat<eT>::fixed<fixed_n_rows, fixed_n_cols>::colptr(const uword in_col) const
  {
  const eT* mem_actual = (use_extra) ? mem_local_extra : mem_local;
  
-  return & mem_actual[in_col*fixed_n_rows];
+  return mem_actual + (in_col*fixed_n_rows);
  }


@@ -1351,6 +1351,10 @@ Row<eT>::fixed<fixed_n_elem>::fixed(const fill::fill_class<fill_type>&)
  if(is_same_type<fill_type, fill::fill_eye  >::yes)  { Mat<eT>::eye();   }
  if(is_same_type<fill_type, fill::fill_randu>::yes)  { Mat<eT>::randu(); }
  if(is_same_type<fill_type, fill::fill_randn>::yes)  { Mat<eT>::randn(); }
+  
+  if(is_same_type<fill_type, fill::fill_nan    >::yes)  { (*this).fill( priv::Datum_helper::nan    <eT>() ); }
+  if(is_same_type<fill_type, fill::fill_pos_inf>::yes)  { (*this).fill( priv::Datum_helper::pos_inf<eT>() ); }
+  if(is_same_type<fill_type, fill::fill_neg_inf>::yes)  { (*this).fill( priv::Datum_helper::neg_inf<eT>() ); }
  }


@@ -527,7 +527,7 @@ SpBase<elem_type,derived>::is_zero(const typename get_pod_type<elem_type>::resul
  
  typedef typename get_pod_type<elem_type>::result T;
  
-  arma_conform_check( (tol < T(0)), "is_zero(): parameter 'tol' must be >= 0" );
+  arma_conform_check( ((tol >= T(0)) == false), "is_zero(): parameter 'tol' must be >= 0" );
  
  const SpProxy<derived> P( (*this).get_ref() );
  
@@ -554,8 +554,8 @@ SpBase<elem_type,derived>::is_zero(const typename get_pod_type<elem_type>::resul
      const T val_real = access::tmp_real(val);
      const T val_imag = access::tmp_imag(val);
      
-      if(eop_aux::arma_abs(val_real) > tol)  { return false; }
-      if(eop_aux::arma_abs(val_imag) > tol)  { return false; }
+      if( (eop_aux::arma_abs(val_real) <= tol) == false )  { return false; }
+      if( (eop_aux::arma_abs(val_imag) <= tol) == false )  { return false; }
      
      ++it;
      }
@@ -564,7 +564,7 @@ SpBase<elem_type,derived>::is_zero(const typename get_pod_type<elem_type>::resul
    {
    while(it != it_end)
      {
-      if(eop_aux::arma_abs(*it) > tol)  { return false; }
+      if( (eop_aux::arma_abs(*it) <= tol) == false )  { return false; }
      
      ++it;
      }
@@ -688,15 +688,22 @@ SpMat<eT>::operator=(const SpMat<eT>& x)
 template<typename eT>
 inline
 SpMat<eT>&
-SpMat<eT>::operator+=(const SpMat<eT>& x)
+SpMat<eT>::operator+=(const SpMat<eT>& X)
  {
  arma_debug_sigprint();
  
  sync_csc();
  
-  SpMat<eT> out = (*this) + x;
-  
-  steal_mem(out);
+  if(X.n_nonzero == 0)
+    {
+    arma_conform_assert_same_size(n_rows, n_cols, X.n_rows, X.n_cols, "addition");
+    }
+  else
+    {
+    SpMat<eT> tmp = (*this) + X;
+    
+    steal_mem(tmp);
+    }
  
  return *this;
  }
@@ -706,15 +713,22 @@ SpMat<eT>::operator+=(const SpMat<eT>& x)
 template<typename eT>
 inline
 SpMat<eT>&
-SpMat<eT>::operator-=(const SpMat<eT>& x)
+SpMat<eT>::operator-=(const SpMat<eT>& X)
  {
  arma_debug_sigprint();
  
  sync_csc();
  
-  SpMat<eT> out = (*this) - x;
-  
-  steal_mem(out);
+  if(X.n_nonzero == 0)
+    {
+    arma_conform_assert_same_size(n_rows, n_cols, X.n_rows, X.n_cols, "subtraction");
+    }
+  else
+    {
+    SpMat<eT> tmp = (*this) - X;
+    
+    steal_mem(tmp);
+    }
  
  return *this;
  }
@@ -724,15 +738,15 @@ SpMat<eT>::operator-=(const SpMat<eT>& x)
 template<typename eT>
 inline
 SpMat<eT>&
-SpMat<eT>::operator*=(const SpMat<eT>& y)
+SpMat<eT>::operator*=(const SpMat<eT>& X)
  {
  arma_debug_sigprint();
  
  sync_csc();
  
-  SpMat<eT> z = (*this) * y;
+  SpMat<eT> tmp = (*this) * X;
  
-  steal_mem(z);
+  steal_mem(tmp);
  
  return *this;
  }
@@ -743,15 +757,24 @@ SpMat<eT>::operator*=(const SpMat<eT>& y)
 template<typename eT>
 inline
 SpMat<eT>&
-SpMat<eT>::operator%=(const SpMat<eT>& y)
+SpMat<eT>::operator%=(const SpMat<eT>& X)
  {
  arma_debug_sigprint();
  
  sync_csc();
  
-  SpMat<eT> z = (*this) % y;
-  
-  steal_mem(z);
+  if(X.n_nonzero == 0)
+    {
+    arma_conform_assert_same_size(n_rows, n_cols, X.n_rows, X.n_cols, "element-wise multiplication");
+    
+    (*this).zeros();
+    }
+  else
+    {
+    SpMat<eT> tmp = (*this) % X;
+    
+    steal_mem(tmp);
+    }
  
  return *this;
  }
@@ -1338,9 +1361,16 @@ SpMat<eT>::operator+=(const SpSubview<eT>& X)
  
  sync_csc();
  
-  SpMat<eT> tmp = (*this) + X;
-  
-  steal_mem(tmp);
+  if(X.n_nonzero == 0)
+    {
+    arma_conform_assert_same_size(n_rows, n_cols, X.n_rows, X.n_cols, "addition");
+    }
+  else
+    {
+    SpMat<eT> tmp = (*this) + X;
+    
+    steal_mem(tmp);
+    }
  
  return *this;
  }
@@ -1356,64 +1386,82 @@ SpMat<eT>::operator-=(const SpSubview<eT>& X)
  
  sync_csc();
  
-  SpMat<eT> tmp = (*this) - X;
-  
-  steal_mem(tmp);
-  
-  return *this;
-  }
-
-
-
-template<typename eT>
-inline
-SpMat<eT>&
-SpMat<eT>::operator*=(const SpSubview<eT>& y)
-  {
-  arma_debug_sigprint();
-  
-  sync_csc();
-  
-  SpMat<eT> z = (*this) * y;
-  
-  steal_mem(z);
-  
-  return *this;
-  }
-
-
-
-template<typename eT>
-inline
-SpMat<eT>&
-SpMat<eT>::operator%=(const SpSubview<eT>& x)
-  {
-  arma_debug_sigprint();
-  
-  sync_csc();
-  
-  SpMat<eT> tmp = (*this) % x;
-  
-  steal_mem(tmp);
-  
-  return *this;
-  }
-
-
-
-template<typename eT>
-inline
-SpMat<eT>&
-SpMat<eT>::operator/=(const SpSubview<eT>& x)
-  {
-  arma_debug_sigprint();
-  
-  arma_conform_assert_same_size(n_rows, n_cols, x.n_rows, x.n_cols, "element-wise division");
-  
-  // There is no pretty way to do this.
-  for(uword elem = 0; elem < n_elem; elem++)
+  if(X.n_nonzero == 0)
    {
-    at(elem) /= x(elem);
+    arma_conform_assert_same_size(n_rows, n_cols, X.n_rows, X.n_cols, "subtraction");
+    }
+  else
+    {
+    SpMat<eT> tmp = (*this) - X;
+    
+    steal_mem(tmp);
+    }
+  
+  return *this;
+  }
+
+
+
+template<typename eT>
+inline
+SpMat<eT>&
+SpMat<eT>::operator*=(const SpSubview<eT>& X)
+  {
+  arma_debug_sigprint();
+  
+  sync_csc();
+  
+  SpMat<eT> tmp = (*this) * X;
+  
+  steal_mem(tmp);
+  
+  return *this;
+  }
+
+
+
+template<typename eT>
+inline
+SpMat<eT>&
+SpMat<eT>::operator%=(const SpSubview<eT>& X)
+  {
+  arma_debug_sigprint();
+  
+  sync_csc();
+  
+  if(X.n_nonzero == 0)
+    {
+    arma_conform_assert_same_size(n_rows, n_cols, X.n_rows, X.n_cols, "element-wise multiplication");
+    
+    (*this).zeros();
+    }
+  else
+    {
+    SpMat<eT> tmp = (*this) % X;
+    
+    steal_mem(tmp);
+    }
+  
+  return *this;
+  }
+
+
+
+template<typename eT>
+inline
+SpMat<eT>&
+SpMat<eT>::operator/=(const SpSubview<eT>& X)
+  {
+  arma_debug_sigprint();
+  
+  // NOTE: use of this function is not advised; it is implemented only for completeness
+  
+  arma_conform_assert_same_size(n_rows, n_cols, X.n_rows, X.n_cols, "element-wise division");
+  
+  for(uword c = 0; c < n_cols; ++c)
+  for(uword r = 0; r < n_rows; ++r)
+    {
+    at(r, c) /= X.at(r, c);
    }
  
  return *this;
@@ -1507,9 +1555,9 @@ SpMat<eT>::operator*=(const SpSubview_col_list<eT,T1>& X)
  
  sync_csc();
  
-  SpMat<eT> z = (*this) * X;
+  SpMat<eT> tmp = (*this) * X;
  
-  steal_mem(z);
+  steal_mem(tmp);
  
  return *this;
  }
@@ -3517,7 +3565,7 @@ SpMat<eT>::is_symmetric(const typename get_pod_type<elem_type>::result tol) cons
  
  if(tol == T(0))  { return (*this).is_symmetric(); }
  
-  arma_conform_check( (tol < T(0)), "is_symmetric(): parameter 'tol' must be >= 0" );
+  arma_conform_check( ((tol >= T(0)) == false), "is_symmetric(): parameter 'tol' must be > 0" );
  
  const SpMat<eT>& A = (*this);
  
@@ -3527,8 +3575,12 @@ SpMat<eT>::is_symmetric(const typename get_pod_type<elem_type>::result tol) cons
  
  if(norm_A == T(0))  { return true; }
  
+  if(arma_isnan(norm_A))  { return false; }
+  
  const T norm_A_Ast = as_scalar( arma::max(sum(abs(A - A.st()), 1), 0) );
  
+  if(arma_isnan(norm_A_Ast))  { return false; }
+  
  return ( (norm_A_Ast / norm_A) <= tol );
  }

@@ -3563,7 +3615,7 @@ SpMat<eT>::is_hermitian(const typename get_pod_type<elem_type>::result tol) cons
  
  if(tol == T(0))  { return (*this).is_hermitian(); }
  
-  arma_conform_check( (tol < T(0)), "is_hermitian(): parameter 'tol' must be >= 0" );
+  arma_conform_check( ((tol >= T(0)) == false), "is_hermitian(): parameter 'tol' must be > 0" );
  
  const SpMat<eT>& A = (*this);
  
@@ -3573,8 +3625,12 @@ SpMat<eT>::is_hermitian(const typename get_pod_type<elem_type>::result tol) cons
  
  if(norm_A == T(0))  { return true; }
  
+  if(arma_isnan(norm_A))  { return false; }
+  
  const T norm_A_At = as_scalar( arma::max(sum(abs(A - A.t()), 1), 0) );
  
+  if(arma_isnan(norm_A_At))  { return false; }
+  
  return ( (norm_A_At / norm_A) <= tol );
  }

@@ -4156,12 +4212,12 @@ SpMat<eT>::clamp(const eT min_val, const eT max_val)
  
  if(is_cx<eT>::no)
    {
-    arma_conform_check( (access::tmp_real(min_val) > access::tmp_real(max_val)), "SpMat::clamp(): min_val must be less than max_val" );
+    arma_conform_check( ((access::tmp_real(min_val) <= access::tmp_real(max_val)) == false), "SpMat::clamp(): min_val must be less than max_val" );
    }
  else
    {
-    arma_conform_check( (access::tmp_real(min_val) > access::tmp_real(max_val)), "SpMat::clamp(): real(min_val) must be less than real(max_val)" );
-    arma_conform_check( (access::tmp_imag(min_val) > access::tmp_imag(max_val)), "SpMat::clamp(): imag(min_val) must be less than imag(max_val)" );
+    arma_conform_check( ((access::tmp_real(min_val) <= access::tmp_real(max_val)) == false), "SpMat::clamp(): real(min_val) must be less than real(max_val)" );
+    arma_conform_check( ((access::tmp_imag(min_val) <= access::tmp_imag(max_val)) == false), "SpMat::clamp(): imag(min_val) must be less than imag(max_val)" );
    }
  
  if(n_nonzero == 0)  { return *this; }
@@ -4341,7 +4397,7 @@ SpMat<eT>::sprandu(const uword in_rows, const uword in_cols, const double densit
  {
  arma_debug_sigprint();
  
-  arma_conform_check( ( (density < double(0)) || (density > double(1)) ), "sprandu(): density must be in the [0,1] interval" );
+  arma_conform_check( ( ((density >= double(0)) == false) || ((density <= double(1)) == false) ), "sprandu(): density must be in the [0,1] interval" );
  
  const uword new_n_nonzero = uword(density * double(in_rows) * double(in_cols) + 0.5);
  
@@ -4418,7 +4474,7 @@ SpMat<eT>::sprandn(const uword in_rows, const uword in_cols, const double densit
  {
  arma_debug_sigprint();
  
-  arma_conform_check( ( (density < double(0)) || (density > double(1)) ), "sprandn(): density must be in the [0,1] interval" );
+  arma_conform_check( ( ((density >= double(0)) == false) || ((density <= double(1)) == false) ), "sprandn(): density must be in the [0,1] interval" );
  
  const uword new_n_nonzero = uword(density * double(in_rows) * double(in_cols) + 0.5);
  
@@ -44,6 +44,8 @@ SpSubview<eT>::SpSubview(const SpMat<eT>& in_m, const uword in_row1, const uword
  
  m.sync_csc();
  
+  if( (n_elem == 0) || (m.n_nonzero == 0) )  { return; }   // (*this).n_nonzero already set to zero
+  
  // count the number of non-zeros in the subview
  uword count = 0;
  
@@ -127,6 +129,8 @@ SpSubview<eT>::operator+=(const eT val)
  
  tmp.fill(val);
  
+  if(n_nonzero == 0)  { return (*this).operator=(tmp); }
+  
  return (*this).operator=( (*this) + tmp );
  }

@@ -319,6 +323,15 @@ SpSubview<eT>::operator+=(const Base<eT, T1>& x)
  {
  arma_debug_sigprint();
  
+  if(n_nonzero == 0)
+    {
+    const quasi_unwrap<T1> U(x.get_ref());
+    
+    arma_conform_assert_same_size(n_rows, n_cols, U.M.n_rows, U.M.n_cols, "addition");
+    
+    return (*this).operator=(U.M);
+    }
+  
  return (*this).operator=( (*this) + x.get_ref() );
  }

@@ -369,6 +382,8 @@ SpSubview<eT>::operator%=(const Base<eT, T1>& x)
  
  arma_conform_assert_same_size(sv.n_rows, sv.n_cols, B.n_rows, B.n_cols, "element-wise multiplication");
  
+  if(n_nonzero == 0)  { return *this; }
+  
  SpMat<eT>& sv_m = access::rw(sv.m);
  
  sv_m.sync_csc();
@@ -555,6 +570,15 @@ SpSubview<eT>::operator+=(const SpBase<eT, T1>& x)
  {
  arma_debug_sigprint();
  
+  if(n_nonzero == 0)
+    {
+    const unwrap_spmat<T1> U(x.get_ref());
+    
+    arma_conform_assert_same_size(n_rows, n_cols, U.M.n_rows, U.M.n_cols, "addition");
+    
+    return (*this).operator_equ_common(U.M);
+    }
+  
  // TODO: implement dedicated machinery
  return (*this).operator=( (*this) + x.get_ref() );
  }
@@ -596,6 +620,15 @@ SpSubview<eT>::operator%=(const SpBase<eT, T1>& x)
  {
  arma_debug_sigprint();
  
+  if(n_nonzero == 0)
+    {
+    const SpProxy<T1> P(x.get_ref());
+    
+    arma_conform_assert_same_size(n_rows, n_cols, P.get_n_rows(), P.get_n_cols(), "element-wise multiplication");
+    
+    return *this;
+    }
+  
  // TODO: implement dedicated machinery
  return (*this).operator=( (*this) % x.get_ref() );
  }
@@ -648,6 +681,8 @@ SpSubview<eT>::for_each(functor F)
  m.sync_csc();
  m.invalidate_cache();
  
+  if(n_nonzero == 0)  { return; }
+  
  const uword lstart_row = aux_row1;
  const uword lend_row   = aux_row1 + n_rows;
  
@@ -704,6 +739,8 @@ SpSubview<eT>::for_each(functor F) const
  
  m.sync_csc();
  
+  if(n_nonzero == 0)  { return; }
+  
  const uword lstart_row = aux_row1;
  const uword lend_row   = aux_row1 + n_rows;
  
@@ -743,6 +780,8 @@ SpSubview<eT>::transform(functor F)
  m.sync_csc();
  m.invalidate_cache();
  
+  if(n_nonzero == 0)  { return; }
+  
  const uword lstart_row = aux_row1;
  const uword lend_row   = aux_row1 + n_rows;
  
@@ -813,6 +852,8 @@ SpSubview<eT>::replace(const eT old_val, const eT new_val)
  m.sync_csc();
  m.invalidate_cache();
  
+  if(n_nonzero == 0)  { return; }
+  
  const uword lstart_row = aux_row1;
  const uword lend_row   = aux_row1 + n_rows;
  
@@ -905,12 +946,12 @@ SpSubview<eT>::clamp(const eT min_val, const eT max_val)
  
  if(is_cx<eT>::no)
    {
-    arma_conform_check( (access::tmp_real(min_val) > access::tmp_real(max_val)), "SpSubview::clamp(): min_val must be less than max_val" );
+    arma_conform_check( ((access::tmp_real(min_val) <= access::tmp_real(max_val)) == false), "SpSubview::clamp(): min_val must be less than max_val" );
    }
  else
    {
-    arma_conform_check( (access::tmp_real(min_val) > access::tmp_real(max_val)), "SpSubview::clamp(): real(min_val) must be less than real(max_val)" );
-    arma_conform_check( (access::tmp_imag(min_val) > access::tmp_imag(max_val)), "SpSubview::clamp(): imag(min_val) must be less than imag(max_val)" );
+    arma_conform_check( ((access::tmp_real(min_val) <= access::tmp_real(max_val)) == false), "SpSubview::clamp(): real(min_val) must be less than real(max_val)" );
+    arma_conform_check( ((access::tmp_imag(min_val) <= access::tmp_imag(max_val)) == false), "SpSubview::clamp(): imag(min_val) must be less than imag(max_val)" );
    }
  
  if((n_elem == 0) || (n_nonzero == 0))  { return; }
@@ -23,7 +23,7 @@

 #define ARMA_VERSION_MAJOR 15
 #define ARMA_VERSION_MINOR 2
-#define ARMA_VERSION_PATCH 3
+#define ARMA_VERSION_PATCH 6
 #define ARMA_VERSION_NAME  "Medium Roast Deluxe"


@@ -994,7 +994,7 @@ arrayops::is_zero(const eT* mem, const uword n_elem, const eT abs_limit, const t
    {
    for(uword i=0; i<n_elem; ++i)
      {
-      if(eop_aux::arma_abs(mem[i]) > abs_limit)  { return false; }
+      if( (eop_aux::arma_abs(mem[i]) <= abs_limit) == false )  { return false; }
      }
    }
  
@@ -1028,8 +1028,8 @@ arrayops::is_zero(const std::complex<T>* mem, const uword n_elem, const T abs_li
      {
      const eT& val = mem[i];
      
-      if(std::abs(std::real(val)) > abs_limit)  { return false; }
-      if(std::abs(std::imag(val)) > abs_limit)  { return false; }
+      if( (std::abs(std::real(val)) <= abs_limit) == false )  { return false; }
+      if( (std::abs(std::imag(val)) <= abs_limit) == false )  { return false; }
      }
    }
  
@@ -330,18 +330,6 @@
  #undef ARMA_OPTIMISE_POWEXPR
 #endif

-#if defined(ARMA_DONT_CHECK_CONFORMANCE)
-  #if defined(ARMA_CHECK_CONFORMANCE) && (ARMA_WARN_LEVEL >= 2)
-    #pragma message ("WARNING: conformance checks disabled")
-  #endif
-  
-  #undef ARMA_CHECK_CONFORMANCE
-#endif
-
-#if defined(ARMA_DONT_CHECK_NONFINITE)
-  #undef ARMA_CHECK_NONFINITE
-#endif
-
 #if defined(ARMA_NO_DEBUG)
  #undef ARMA_DEBUG
  #undef ARMA_EXTRA_DEBUG
@@ -361,6 +349,18 @@
  #define ARMA_WARN_LEVEL 3
 #endif

+#if defined(ARMA_DONT_CHECK_CONFORMANCE)
+  #if defined(ARMA_CHECK_CONFORMANCE) && (ARMA_WARN_LEVEL >= 2)
+    #pragma message ("WARNING: conformance checks disabled")
+  #endif
+  
+  #undef ARMA_CHECK_CONFORMANCE
+#endif
+
+#if defined(ARMA_DONT_CHECK_NONFINITE)
+  #undef ARMA_CHECK_NONFINITE
+#endif
+
 #if defined(ARMA_DONT_PRINT_EXCEPTIONS)
  #undef ARMA_PRINT_EXCEPTIONS
 #endif
@@ -330,18 +330,6 @@
  #undef ARMA_OPTIMISE_POWEXPR
 #endif

-#if defined(ARMA_DONT_CHECK_CONFORMANCE)
-  #if defined(ARMA_CHECK_CONFORMANCE) && (ARMA_WARN_LEVEL >= 2)
-    #pragma message ("WARNING: conformance checks disabled")
-  #endif
-  
-  #undef ARMA_CHECK_CONFORMANCE
-#endif
-
-#if defined(ARMA_DONT_CHECK_NONFINITE)
-  #undef ARMA_CHECK_NONFINITE
-#endif
-
 #if defined(ARMA_NO_DEBUG)
  #undef ARMA_DEBUG
  #undef ARMA_EXTRA_DEBUG
@@ -361,6 +349,18 @@
  #define ARMA_WARN_LEVEL 3
 #endif

+#if defined(ARMA_DONT_CHECK_CONFORMANCE)
+  #if defined(ARMA_CHECK_CONFORMANCE) && (ARMA_WARN_LEVEL >= 2)
+    #pragma message ("WARNING: conformance checks disabled")
+  #endif
+  
+  #undef ARMA_CHECK_CONFORMANCE
+#endif
+
+#if defined(ARMA_DONT_CHECK_NONFINITE)
+  #undef ARMA_CHECK_NONFINITE
+#endif
+
 #if defined(ARMA_DONT_PRINT_EXCEPTIONS)
  #undef ARMA_PRINT_EXCEPTIONS
 #endif
@@ -62,11 +62,14 @@ namespace priv
      }
    
    
+    //
+    
+    
    template<typename eT>
    static
    constexpr
    typename arma_real_only<eT>::result
-    inf(typename arma_real_only<eT>::result* junk = nullptr)
+    pos_inf(typename arma_real_only<eT>::result* junk = nullptr)
      {
      arma_ignore(junk);
      
@@ -78,13 +81,13 @@ namespace priv
    static
    constexpr
    typename arma_cx_only<eT>::result
-    inf(typename arma_cx_only<eT>::result* junk = nullptr)
+    pos_inf(typename arma_cx_only<eT>::result* junk = nullptr)
      {
      arma_ignore(junk);
      
      typedef typename get_pod_type<eT>::result T;
      
-      return eT( Datum_helper::inf<T>(), Datum_helper::inf<T>() );
+      return eT( Datum_helper::pos_inf<T>(), Datum_helper::pos_inf<T>() );
      }
    
    
@@ -92,12 +95,54 @@ namespace priv
    static
    constexpr
    typename arma_integral_only<eT>::result
-    inf(typename arma_integral_only<eT>::result* junk = nullptr)
+    pos_inf(typename arma_integral_only<eT>::result* junk = nullptr)
      {
      arma_ignore(junk);
      
      return std::numeric_limits<eT>::max();
      }
+    
+    
+    //
+    
+    
+    template<typename eT>
+    static
+    constexpr
+    typename arma_real_only<eT>::result
+    neg_inf(typename arma_real_only<eT>::result* junk = nullptr)
+      {
+      arma_ignore(junk);
+      
+      return (std::numeric_limits<eT>::has_infinity) ? eT(-std::numeric_limits<eT>::infinity()) : eT(std::numeric_limits<eT>::lowest());
+      }
+    
+    
+    template<typename eT>
+    static
+    constexpr
+    typename arma_cx_only<eT>::result
+    neg_inf(typename arma_cx_only<eT>::result* junk = nullptr)
+      {
+      arma_ignore(junk);
+      
+      typedef typename get_pod_type<eT>::result T;
+      
+      return eT( Datum_helper::neg_inf<T>(), Datum_helper::neg_inf<T>() );
+      }
+    
+    
+    template<typename eT>
+    static
+    constexpr
+    typename arma_integral_only<eT>::result
+    neg_inf(typename arma_integral_only<eT>::result* junk = nullptr)
+      {
+      arma_ignore(junk);
+      
+      return std::numeric_limits<eT>::lowest();
+      }
+    
    };
  }

@@ -125,7 +170,9 @@ struct Datum
  static const eT log_min;      //!< log of the minimum representable value
  static const eT log_max;      //!< log of the maximum representable value
  static const eT nan;          //!< "not a number"
-  static const eT inf;          //!< infinity 
+  static const eT inf;          //!< positive infinity
+  static const eT pos_inf;      //!< positive infinity
+  static const eT neg_inf;      //!< negative infinity

  // 
  
@@ -176,7 +223,9 @@ template<typename eT> const eT Datum<eT>::eps         = std::numeric_limits<eT>:
 template<typename eT> const eT Datum<eT>::log_min     = std::log(std::numeric_limits<eT>::min());
 template<typename eT> const eT Datum<eT>::log_max     = std::log(std::numeric_limits<eT>::max());
 template<typename eT> const eT Datum<eT>::nan         = priv::Datum_helper::nan<eT>();
-template<typename eT> const eT Datum<eT>::inf         = priv::Datum_helper::inf<eT>();
+template<typename eT> const eT Datum<eT>::inf         = priv::Datum_helper::pos_inf<eT>();
+template<typename eT> const eT Datum<eT>::pos_inf     = priv::Datum_helper::pos_inf<eT>();
+template<typename eT> const eT Datum<eT>::neg_inf     = priv::Datum_helper::neg_inf<eT>();

 template<typename eT> const eT Datum<eT>::m_u       = eT(1.66053906892e-27);
 template<typename eT> const eT Datum<eT>::N_A       = eT(6.02214076e23);
@@ -134,15 +134,25 @@ diagview<eT>::operator+=(const eT val)
  {
  arma_debug_sigprint();
  
-  Mat<eT>& t_m = const_cast< Mat<eT>& >(m);
+  diagview<eT>& d = *this;
  
-  const uword t_n_elem     = n_elem;
-  const uword t_row_offset = row_offset;
-  const uword t_col_offset = col_offset;
+  Mat<eT>& d_m = const_cast< Mat<eT>& >(d.m);
  
-  for(uword ii=0; ii < t_n_elem; ++ii)
+  const uword d_n_elem     = d.n_elem;
+  const uword d_row_offset = d.row_offset;
+  const uword d_col_offset = d.col_offset;
+  
+  uword ii,jj;
+  
+  for(ii=0, jj=1; jj < d_n_elem; ii+=2, jj+=2)
    {
-    t_m.at( ii + t_row_offset,  ii + t_col_offset) += val;
+    d_m.at( ii + d_row_offset,  ii + d_col_offset) += val;
+    d_m.at( jj + d_row_offset,  jj + d_col_offset) += val;
+    }
+  
+  if(ii < d_n_elem)
+    {
+    d_m.at( ii + d_row_offset,  ii + d_col_offset) += val;
    }
  }

@@ -155,15 +165,25 @@ diagview<eT>::operator-=(const eT val)
  {
  arma_debug_sigprint();
  
-  Mat<eT>& t_m = const_cast< Mat<eT>& >(m);
+  diagview<eT>& d = *this;
  
-  const uword t_n_elem     = n_elem;
-  const uword t_row_offset = row_offset;
-  const uword t_col_offset = col_offset;
+  Mat<eT>& d_m = const_cast< Mat<eT>& >(d.m);
  
-  for(uword ii=0; ii < t_n_elem; ++ii)
+  const uword d_n_elem     = d.n_elem;
+  const uword d_row_offset = d.row_offset;
+  const uword d_col_offset = d.col_offset;
+  
+  uword ii,jj;
+  
+  for(ii=0, jj=1; jj < d_n_elem; ii+=2, jj+=2)
    {
-    t_m.at( ii + t_row_offset,  ii + t_col_offset) -= val;
+    d_m.at( ii + d_row_offset,  ii + d_col_offset) -= val;
+    d_m.at( jj + d_row_offset,  jj + d_col_offset) -= val;
+    }
+  
+  if(ii < d_n_elem)
+    {
+    d_m.at( ii + d_row_offset,  ii + d_col_offset) -= val;
    }
  }

@@ -176,15 +196,25 @@ diagview<eT>::operator*=(const eT val)
  {
  arma_debug_sigprint();
  
-  Mat<eT>& t_m = const_cast< Mat<eT>& >(m);
+  diagview<eT>& d = *this;
  
-  const uword t_n_elem     = n_elem;
-  const uword t_row_offset = row_offset;
-  const uword t_col_offset = col_offset;
+  Mat<eT>& d_m = const_cast< Mat<eT>& >(d.m);
  
-  for(uword ii=0; ii < t_n_elem; ++ii)
+  const uword d_n_elem     = d.n_elem;
+  const uword d_row_offset = d.row_offset;
+  const uword d_col_offset = d.col_offset;
+  
+  uword ii,jj;
+  
+  for(ii=0, jj=1; jj < d_n_elem; ii+=2, jj+=2)
    {
-    t_m.at( ii + t_row_offset,  ii + t_col_offset) *= val;
+    d_m.at( ii + d_row_offset,  ii + d_col_offset) *= val;
+    d_m.at( jj + d_row_offset,  jj + d_col_offset) *= val;
+    }
+  
+  if(ii < d_n_elem)
+    {
+    d_m.at( ii + d_row_offset,  ii + d_col_offset) *= val;
    }
  }

@@ -197,15 +227,25 @@ diagview<eT>::operator/=(const eT val)
  {
  arma_debug_sigprint();
  
-  Mat<eT>& t_m = const_cast< Mat<eT>& >(m);
+  diagview<eT>& d = *this;
  
-  const uword t_n_elem     = n_elem;
-  const uword t_row_offset = row_offset;
-  const uword t_col_offset = col_offset;
+  Mat<eT>& d_m = const_cast< Mat<eT>& >(d.m);
  
-  for(uword ii=0; ii < t_n_elem; ++ii)
+  const uword d_n_elem     = d.n_elem;
+  const uword d_row_offset = d.row_offset;
+  const uword d_col_offset = d.col_offset;
+  
+  uword ii,jj;
+  
+  for(ii=0, jj=1; jj < d_n_elem; ii+=2, jj+=2)
    {
-    t_m.at( ii + t_row_offset,  ii + t_col_offset) /= val;
+    d_m.at( ii + d_row_offset,  ii + d_col_offset) /= val;
+    d_m.at( jj + d_row_offset,  jj + d_col_offset) /= val;
+    }
+  
+  if(ii < d_n_elem)
+    {
+    d_m.at( ii + d_row_offset,  ii + d_col_offset) /= val;
    }
  }

@@ -236,6 +276,12 @@ diagview<eT>::operator= (const Base<eT,T1>& o)
    "diagview: given object has incompatible size"
    );
  
+  constexpr bool is_gen_zeros = (is_same_type< T1, Gen<Mat<eT>, gen_zeros> >::yes) || (is_same_type< T1, Gen<Col<eT>, gen_zeros> >::yes);
+  constexpr bool is_gen_ones  = (is_same_type< T1, Gen<Mat<eT>, gen_ones > >::yes) || (is_same_type< T1, Gen<Col<eT>, gen_ones > >::yes);
+  
+  if(is_gen_zeros)  { d.zeros(); return; }
+  if(is_gen_ones )  { d.ones();  return; }
+  
  const bool have_alias = P.is_alias(d_m);
  
  if(have_alias)  { arma_debug_print("aliasing detected"); }
@@ -948,13 +994,25 @@ diagview<eT>::fill(const eT val)
  {
  arma_debug_sigprint();
  
-  Mat<eT>& x = const_cast< Mat<eT>& >(m);
+  diagview<eT>& d = *this;
  
-  const uword local_n_elem = n_elem;
+  Mat<eT>& d_m = const_cast< Mat<eT>& >(d.m);
  
-  for(uword ii=0; ii < local_n_elem; ++ii)
+  const uword d_n_elem     = d.n_elem;
+  const uword d_row_offset = d.row_offset;
+  const uword d_col_offset = d.col_offset;
+  
+  uword ii,jj;
+  
+  for(ii=0, jj=1; jj < d_n_elem; ii+=2, jj+=2)
    {
-    x.at(ii+row_offset, ii+col_offset) = val;
+    d_m.at( ii + d_row_offset,  ii + d_col_offset) = val;
+    d_m.at( jj + d_row_offset,  jj + d_col_offset) = val;
+    }
+  
+  if(ii < d_n_elem)
+    {
+    d_m.at( ii + d_row_offset,  ii + d_col_offset) = val;
    }
  }

@@ -373,29 +373,37 @@ inline
 std::string
 diskio::gen_tmp_name(const std::string& x)
  {
-  union { uword val; void* ptr; } u;
+  arma_debug_sigprint();
  
-  u.val = uword(0);
-  u.ptr = const_cast<std::string*>(&x);
+  const char* charlist = "0123456789abcdefghijklmnopqrstuvwxyz";
+  const char* suffix1  = ".!";
  
-  const u16 a = u16( (u.val >> 8)   & 0xFFFF );
-  const u16 b = u16( (std::clock()) & 0xFFFF );
+  constexpr std::size_t charlist_length = 36;
+  constexpr std::size_t  suffix1_length =  2;
+  constexpr std::size_t  suffix2_length =  6;
  
-  std::ostringstream ss;
+  typedef typename std::minstd_rand::result_type local_seed_type;
  
-  ss << x << ".tmp_";
+  std::minstd_rand                           local_engine;
+  std::uniform_int_distribution<std::size_t> local_distr(0, charlist_length - 1);
  
-  ss.setf(std::ios_base::hex, std::ios_base::basefield);
+  local_engine.seed( static_cast<local_seed_type>( (std::clock()) & 0xFFFF ) );
  
-  ss.width(4);
-  ss.fill('0');
-  ss << a;
+  const std::size_t x_length = x.length();
  
-  ss.width(4);
-  ss.fill('0');
-  ss << b;
+  std::string out(x_length + suffix1_length + suffix2_length, '0');  // create string filled with char '0' (not 0)
  
-  return ss.str();
+  std::size_t count = 0;
+  
+  for(; count < x_length; ++count)  { out[count] = x[count]; }
+  
+  for(std::size_t i=0; i < suffix1_length; ++i, ++count)  { out[count] = suffix1[i]; }
+  
+  local_distr(local_engine);  // ignore first random number
+  
+  for(std::size_t i=0; i < suffix2_length; ++i, ++count)  { out[count] = charlist[ local_distr(local_engine)]; }
+  
+  return out;
  }


@@ -22,22 +22,29 @@

 namespace fill
  {
-  struct fill_none  {};
-  struct fill_zeros {};
-  struct fill_ones  {};
-  struct fill_eye   {};
-  struct fill_randu {};
-  struct fill_randn {};
+  struct fill_none    {};
+  struct fill_zeros   {};
+  struct fill_ones    {};
+  struct fill_eye     {};
+  struct fill_randu   {};
+  struct fill_randn   {};
+  struct fill_nan     {};
+  struct fill_pos_inf {};
+  struct fill_neg_inf {};
  
  template<typename fill_type> 
  struct fill_class { inline constexpr fill_class() {} };
  
-  static constexpr fill_class<fill_none > none;
-  static constexpr fill_class<fill_zeros> zeros;
-  static constexpr fill_class<fill_ones > ones;
-  static constexpr fill_class<fill_eye  > eye;
-  static constexpr fill_class<fill_randu> randu;
-  static constexpr fill_class<fill_randn> randn;
+  static constexpr fill_class<fill_none   > none;
+  static constexpr fill_class<fill_zeros  > zeros;
+  static constexpr fill_class<fill_ones   > ones;
+  static constexpr fill_class<fill_eye    > eye;
+  static constexpr fill_class<fill_randu  > randu;
+  static constexpr fill_class<fill_randn  > randn;
+  static constexpr fill_class<fill_nan    > nan;
+  static constexpr fill_class<fill_pos_inf> inf;
+  static constexpr fill_class<fill_pos_inf> pos_inf;
+  static constexpr fill_class<fill_neg_inf> neg_inf;
  
  //
  
@@ -110,8 +110,8 @@ internal_approx_equal_worker
  
  arma_conform_check( ((use_abs_diff == false) && (use_rel_diff == false)), "internal_approx_equal_worker(): both 'use_abs_diff' and 'use_rel_diff' are false" );
  
-  if(use_abs_diff)  { arma_conform_check( cond_rel< is_signed<T>::value >::lt(abs_tol, T(0)), "approx_equal(): argument 'abs_tol' must be >= 0" ); }
-  if(use_rel_diff)  { arma_conform_check( cond_rel< is_signed<T>::value >::lt(rel_tol, T(0)), "approx_equal(): argument 'rel_tol' must be >= 0" ); }
+  if(use_abs_diff)  { arma_conform_check( (cond_rel< is_signed<T>::value >::lt(abs_tol, T(0)) || arma_isnan(abs_tol)), "approx_equal(): argument 'abs_tol' must be >= 0" ); }
+  if(use_rel_diff)  { arma_conform_check( (cond_rel< is_signed<T>::value >::lt(rel_tol, T(0)) || arma_isnan(rel_tol)), "approx_equal(): argument 'rel_tol' must be >= 0" ); }
  
  const Proxy<T1> PA(A.get_ref());
  const Proxy<T2> PB(B.get_ref());
@@ -203,8 +203,8 @@ internal_approx_equal_worker
  
  arma_conform_check( ((use_abs_diff == false) && (use_rel_diff == false)), "internal_approx_equal_worker(): both 'use_abs_diff' and 'use_rel_diff' are false" );
  
-  if(use_abs_diff)  { arma_conform_check( cond_rel< is_signed<T>::value >::lt(abs_tol, T(0)), "approx_equal(): argument 'abs_tol' must be >= 0" ); }
-  if(use_rel_diff)  { arma_conform_check( cond_rel< is_signed<T>::value >::lt(rel_tol, T(0)), "approx_equal(): argument 'rel_tol' must be >= 0" ); }
+  if(use_abs_diff)  { arma_conform_check( (cond_rel< is_signed<T>::value >::lt(abs_tol, T(0)) || arma_isnan(abs_tol)), "approx_equal(): argument 'abs_tol' must be >= 0" ); }
+  if(use_rel_diff)  { arma_conform_check( (cond_rel< is_signed<T>::value >::lt(rel_tol, T(0)) || arma_isnan(rel_tol)), "approx_equal(): argument 'rel_tol' must be >= 0" ); }
  
  const ProxyCube<T1> PA(A.get_ref());
  const ProxyCube<T2> PB(B.get_ref());
@@ -418,7 +418,7 @@ approx_equal(const SpBase<typename T1::elem_type,T1>& A, const SpBase<typename T
  
  arma_conform_check( (sig == 'r'), "approx_equal(): only the \"absdiff\" method is currently implemented for sparse matrices" );
  
-  arma_conform_check( cond_rel< is_signed<T>::value >::lt(tol, T(0)), "approx_equal(): argument 'tol' must be >= 0" );
+  arma_conform_check( (cond_rel< is_signed<T>::value >::lt(tol, T(0)) || arma_isnan(tol)), "approx_equal(): argument 'tol' must be >= 0" );
  
  const unwrap_spmat<T1> UA(A.get_ref());
  const unwrap_spmat<T2> UB(B.get_ref());
@@ -460,8 +460,8 @@ approx_equal(const SpBase<typename T1::elem_type,T1>& A, const SpBase<typename T
  
  arma_conform_check( ((sig == 'r') || (sig == 'b')), "approx_equal(): only the \"absdiff\" method is currently implemented for sparse matrices" );
  
-  arma_conform_check( cond_rel< is_signed<T>::value >::lt(abs_tol, T(0)), "approx_equal(): argument 'abs_tol' must be >= 0" );
-  arma_conform_check( cond_rel< is_signed<T>::value >::lt(rel_tol, T(0)), "approx_equal(): argument 'rel_tol' must be >= 0" );
+  arma_conform_check( (cond_rel< is_signed<T>::value >::lt(abs_tol, T(0)) || arma_isnan(abs_tol)), "approx_equal(): argument 'abs_tol' must be >= 0" );
+  arma_conform_check( (cond_rel< is_signed<T>::value >::lt(rel_tol, T(0)) || arma_isnan(rel_tol)), "approx_equal(): argument 'rel_tol' must be >= 0" );
  
  return approx_equal(A.get_ref(), B.get_ref(), "abs", abs_tol);
  }
@@ -97,12 +97,12 @@ clamp(const SpBase<typename T1::elem_type,T1>& X, const typename T1::elem_type m
  
  if(is_cx<eT>::no)
    {
-    arma_conform_check( (access::tmp_real(min_val) > access::tmp_real(max_val)), "clamp(): min_val must be less than max_val" );
+    arma_conform_check( ((access::tmp_real(min_val) <= access::tmp_real(max_val)) == false), "clamp(): min_val must be less than max_val" );
    }
  else
    {
-    arma_conform_check( (access::tmp_real(min_val) > access::tmp_real(max_val)), "clamp(): real(min_val) must be less than real(max_val)" );
-    arma_conform_check( (access::tmp_imag(min_val) > access::tmp_imag(max_val)), "clamp(): imag(min_val) must be less than imag(max_val)" );
+    arma_conform_check( ((access::tmp_real(min_val) <= access::tmp_real(max_val)) == false), "clamp(): real(min_val) must be less than real(max_val)" );
+    arma_conform_check( ((access::tmp_imag(min_val) <= access::tmp_imag(max_val)) == false), "clamp(): imag(min_val) must be less than imag(max_val)" );
    }
  
  SpMat<eT> out = X.get_ref();
@@ -47,7 +47,7 @@ rande(const uword n_rows, const uword n_cols, const distr_param& param = distr_p
  
  param.get_double_vals(lambda, unused);
  
-  arma_conform_check( (lambda <= double(0)), "rande(): incorrect distribution parameters; lambda must be greater than zero" );
+  arma_conform_check( ((lambda > double(0)) == false), "rande(): incorrect distribution parameters; lambda must be greater than zero" );
  
  obj_type out(n_rows, n_cols, arma_nozeros_indicator());
  
@@ -138,7 +138,7 @@ rande(const distr_param& param = distr_param())
  
  param.get_double_vals(lambda, unused);
  
-  arma_conform_check( (lambda <= double(0)), "rande(): incorrect distribution parameters; lambda must be greater than zero" );
+  arma_conform_check( ((lambda > double(0)) == false), "rande(): incorrect distribution parameters; lambda must be greater than zero" );
  
  double out_val = double(0);
  
@@ -162,7 +162,7 @@ rande(const distr_param& param = distr_param())
  
  param.get_double_vals(lambda, unused);
  
-  arma_conform_check( (lambda <= double(0)), "rande(): incorrect distribution parameters; lambda must be greater than zero" );
+  arma_conform_check( ((lambda > double(0)) == false), "rande(): incorrect distribution parameters; lambda must be greater than zero" );
  
  eT out_val = eT(0);
  
@@ -189,7 +189,7 @@ rande(const uword n_rows, const uword n_cols, const uword n_slices, const distr_
  
  param.get_double_vals(lambda, unused);
  
-  arma_conform_check( (lambda <= double(0)), "rande(): incorrect distribution parameters; lambda must be greater than zero" );
+  arma_conform_check( ((lambda > double(0)) == false), "rande(): incorrect distribution parameters; lambda must be greater than zero" );
  
  cube_type out(n_rows, n_cols, n_slices, arma_nozeros_indicator());
  
@@ -47,7 +47,7 @@ randg(const uword n_rows, const uword n_cols, const distr_param& param = distr_p
  
  param.get_double_vals(a,b);
  
-  arma_conform_check( ((a <= double(0)) || (b <= double(0))), "randg(): incorrect distribution parameters; a and b must be greater than zero" );
+  arma_conform_check( ( ((a > double(0)) == false) || ((b > double(0)) == false) ), "randg(): incorrect distribution parameters; a and b must be greater than zero" );
  
  obj_type out(n_rows, n_cols, arma_nozeros_indicator());
  
@@ -138,7 +138,7 @@ randg(const distr_param& param = distr_param())
  
  param.get_double_vals(a,b);
  
-  arma_conform_check( ((a <= double(0)) || (b <= double(0))), "randg(): incorrect distribution parameters; a and b must be greater than zero" );
+  arma_conform_check( ( ((a > double(0)) == false) || ((b > double(0)) == false) ), "randg(): incorrect distribution parameters; a and b must be greater than zero" );
  
  double out_val = double(0);
  
@@ -162,7 +162,7 @@ randg(const distr_param& param = distr_param())
  
  param.get_double_vals(a,b);
  
-  arma_conform_check( ((a <= double(0)) || (b <= double(0))), "randg(): incorrect distribution parameters; a and b must be greater than zero" );
+  arma_conform_check( ( ((a > double(0)) == false) || ((b > double(0)) == false) ), "randg(): incorrect distribution parameters; a and b must be greater than zero" );
  
  eT out_val = eT(0);
  
@@ -189,7 +189,7 @@ randg(const uword n_rows, const uword n_cols, const uword n_slices, const distr_
  
  param.get_double_vals(a,b);
  
-  arma_conform_check( ((a <= double(0)) || (b <= double(0))), "randg(): incorrect distribution parameters; a and b must be greater than zero" );
+  arma_conform_check( ( ((a > double(0)) == false) || ((b > double(0)) == false) ), "randg(): incorrect distribution parameters; a and b must be greater than zero" );
  
  cube_type out(n_rows, n_cols, n_slices, arma_nozeros_indicator());
  
@@ -47,7 +47,7 @@ randi(const uword n_rows, const uword n_cols, const distr_param& param = distr_p
  
  param.get_int_vals(a,b);
  
-  arma_conform_check( (a > b), "randi(): incorrect distribution parameters; a must be less than b" );
+  arma_conform_check( ((a <= b) == false), "randi(): incorrect distribution parameters; a must be less than b" );
  
  obj_type out(n_rows, n_cols, arma_nozeros_indicator());
  
@@ -142,7 +142,7 @@ randi(const distr_param& param)
  
  param.get_int_vals(a,b);
  
-  arma_conform_check( (a > b), "randi(): incorrect distribution parameters; a must be less than b" );
+  arma_conform_check( ((a <= b) == false), "randi(): incorrect distribution parameters; a must be less than b" );
  
  sword out_val = sword(0);
  
@@ -166,7 +166,7 @@ randi(const distr_param& param)
  
  param.get_int_vals(a,b);
  
-  arma_conform_check( (a > b), "randi(): incorrect distribution parameters; a must be less than b" );
+  arma_conform_check( ((a <= b) == false), "randi(): incorrect distribution parameters; a must be less than b" );
  
  eT out_val = eT(0);
  
@@ -218,7 +218,7 @@ randi(const uword n_rows, const uword n_cols, const uword n_slices, const distr_
  
  param.get_int_vals(a,b);
  
-  arma_conform_check( (a > b), "randi(): incorrect distribution parameters; a must be less than b" );
+  arma_conform_check( ((a <= b) == false), "randi(): incorrect distribution parameters; a must be less than b" );
  
  cube_type out(n_rows, n_cols, n_slices, arma_nozeros_indicator());
  
@@ -62,7 +62,7 @@ randn(const distr_param& param)
  
  param.get_double_vals(mu,sd);
  
-  arma_conform_check( (sd <= double(0)), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
+  arma_conform_check( ((sd > double(0)) == false), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
  
  const double val = double(arma_rng::randn<double>());
  
@@ -86,7 +86,7 @@ randn(const distr_param& param)
  
  param.get_double_vals(mu,sd);
  
-  arma_conform_check( (sd <= double(0)), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
+  arma_conform_check( ((sd > double(0)) == false), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
  
  eT val = eT(0);
  
@@ -119,7 +119,7 @@ randn(const uword n_elem, const distr_param& param = distr_param())
    
    param.get_double_vals(mu,sd);
    
-    arma_conform_check( (sd <= double(0)), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
+    arma_conform_check( ((sd > double(0)) == false), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
    
    arma_rng::randn<double>::fill(out.memptr(), n_elem, mu, sd);
    }
@@ -156,7 +156,7 @@ randn(const uword n_elem, const distr_param& param = distr_param(), const typena
    
    param.get_double_vals(mu,sd);
    
-    arma_conform_check( (sd <= double(0)), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
+    arma_conform_check( ((sd > double(0)) == false), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
    
    arma_rng::randn<eT>::fill(out.memptr(), out.n_elem, mu, sd);
    }
@@ -188,7 +188,7 @@ randn(const uword n_rows, const uword n_cols, const distr_param& param = distr_p
    
    param.get_double_vals(mu,sd);
    
-    arma_conform_check( (sd <= double(0)), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
+    arma_conform_check( ((sd > double(0)) == false), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
    
    arma_rng::randn<double>::fill(out.memptr(), out.n_elem, mu, sd);
    }
@@ -237,7 +237,7 @@ randn(const uword n_rows, const uword n_cols, const distr_param& param = distr_p
    
    param.get_double_vals(mu,sd);
    
-    arma_conform_check( (sd <= double(0)), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
+    arma_conform_check( ((sd > double(0)) == false), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
    
    arma_rng::randn<eT>::fill(out.memptr(), out.n_elem, mu, sd);
    }
@@ -284,7 +284,7 @@ randn(const uword n_rows, const uword n_cols, const uword n_slices, const distr_
    
    param.get_double_vals(mu,sd);
    
-    arma_conform_check( (sd <= double(0)), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
+    arma_conform_check( ((sd > double(0)) == false), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
    
    arma_rng::randn<double>::fill(out.memptr(), out.n_elem, mu, sd);
    }
@@ -330,7 +330,7 @@ randn(const uword n_rows, const uword n_cols, const uword n_slices, const distr_
    
    param.get_double_vals(mu,sd);
    
-    arma_conform_check( (sd <= double(0)), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
+    arma_conform_check( ((sd > double(0)) == false), "randn(): incorrect distribution parameters; standard deviation must be > 0" );
    
    arma_rng::randn<eT>::fill(out.memptr(), out.n_elem, mu, sd);
    }
@@ -62,7 +62,7 @@ randu(const distr_param& param)
  
  param.get_double_vals(a,b);
  
-  arma_conform_check( (a >= b), "randu(): incorrect distribution parameters; a must be less than b" );
+  arma_conform_check( ((a < b) == false), "randu(): incorrect distribution parameters; a must be less than b" );
  
  const double val = double(arma_rng::randu<double>());
  
@@ -86,7 +86,7 @@ randu(const distr_param& param)
  
  param.get_double_vals(a,b);
  
-  arma_conform_check( (a >= b), "randu(): incorrect distribution parameters; a must be less than b" );
+  arma_conform_check( ((a < b) == false), "randu(): incorrect distribution parameters; a must be less than b" );
  
  eT val = eT(0);
  
@@ -119,7 +119,7 @@ randu(const uword n_elem, const distr_param& param = distr_param())
    
    param.get_double_vals(a,b);
    
-    arma_conform_check( (a >= b), "randu(): incorrect distribution parameters; a must be less than b" );
+    arma_conform_check( ((a < b) == false), "randu(): incorrect distribution parameters; a must be less than b" );
    
    arma_rng::randu<double>::fill(out.memptr(), n_elem, a, b);
    }
@@ -156,7 +156,7 @@ randu(const uword n_elem, const distr_param& param = distr_param(), const typena
    
    param.get_double_vals(a,b);
    
-    arma_conform_check( (a >= b), "randu(): incorrect distribution parameters; a must be less than b" );
+    arma_conform_check( ((a < b) == false), "randu(): incorrect distribution parameters; a must be less than b" );
    
    arma_rng::randu<eT>::fill(out.memptr(), out.n_elem, a, b);
    }
@@ -188,7 +188,7 @@ randu(const uword n_rows, const uword n_cols, const distr_param& param = distr_p
    
    param.get_double_vals(a,b);
    
-    arma_conform_check( (a >= b), "randu(): incorrect distribution parameters; a must be less than b" );
+    arma_conform_check( ((a < b) == false), "randu(): incorrect distribution parameters; a must be less than b" );
    
    arma_rng::randu<double>::fill(out.memptr(), out.n_elem, a, b);
    }
@@ -237,7 +237,7 @@ randu(const uword n_rows, const uword n_cols, const distr_param& param = distr_p
    
    param.get_double_vals(a,b);
    
-    arma_conform_check( (a >= b), "randu(): incorrect distribution parameters; a must be less than b" );
+    arma_conform_check( ((a < b) == false), "randu(): incorrect distribution parameters; a must be less than b" );
    
    arma_rng::randu<eT>::fill(out.memptr(), out.n_elem, a, b);
    }
@@ -284,7 +284,7 @@ randu(const uword n_rows, const uword n_cols, const uword n_slices, const distr_
    
    param.get_double_vals(a,b);
    
-    arma_conform_check( (a >= b), "randu(): incorrect distribution parameters; a must be less than b" );
+    arma_conform_check( ((a < b) == false), "randu(): incorrect distribution parameters; a must be less than b" );
    
    arma_rng::randu<double>::fill(out.memptr(), out.n_elem, a, b);
    }
@@ -330,7 +330,7 @@ randu(const uword n_rows, const uword n_cols, const uword n_slices, const distr_
    
    param.get_double_vals(a,b);
    
-    arma_conform_check( (a >= b), "randu(): incorrect distribution parameters; a must be less than b" );
+    arma_conform_check( ((a < b) == false), "randu(): incorrect distribution parameters; a must be less than b" );
    
    arma_rng::randu<eT>::fill(out.memptr(), out.n_elem, a, b);
    }
@@ -55,7 +55,7 @@ spsolve_helper
  
  const superlu_opts& opts = (settings.id == 1) ? static_cast<const superlu_opts&>(settings) : superlu_opts_default;
  
-  arma_conform_check( ( (opts.pivot_thresh < double(0)) || (opts.pivot_thresh > double(1)) ), "spsolve(): pivot_thresh must be in the [0,1] interval" );
+  arma_conform_check( ( ((opts.pivot_thresh >= double(0)) == false) || ((opts.pivot_thresh <= double(1)) == false) ), "spsolve(): pivot_thresh must be in the [0,1] interval" );
  
  if(sig == 's')  // SuperLU solver
    {
@@ -110,12 +110,12 @@ spsolve_helper
  
  if( (status == false) && (rcond > T(0)) )
    {
-    arma_warn(2, "spsolve(): system is singular (rcond: ", rcond, ")");
+    arma_warn(2, "spsolve(): system is singular; rcond: ", rcond);
    }
  
  if( (status == true) && (rcond > T(0)) && (rcond < std::numeric_limits<T>::epsilon()) )
    {
-    arma_warn(2, "solve(): solution computed, but system is singular to working precision (rcond: ", rcond, ")");
+    arma_warn(2, "spsolve(): solution computed, but system is singular to working precision; rcond: ", rcond);
    }
  
  return status;
@@ -47,7 +47,7 @@ svds_helper
    "svds(): two or more output objects are the same object"
    );
  
-  arma_conform_check( (tol < T(0)), "svds(): tol must be >= 0" );
+  arma_conform_check( ((tol >= T(0)) == false), "svds(): tol must be >= 0" );
  
  const unwrap_spmat<T1> tmp(X.get_ref());
  const SpMat<eT>& A =   tmp.M;
@@ -171,7 +171,7 @@ svds_helper
    "svds(): two or more output objects are the same object"
    );
  
-  arma_conform_check( (tol < T(0)), "svds(): tol must be >= 0" );
+  arma_conform_check( ((tol >= T(0)) == false), "svds(): tol must be >= 0" );
  
  const unwrap_spmat<T1> tmp(X.get_ref());
  const SpMat<eT>& A =   tmp.M;
@@ -380,7 +380,7 @@ glue_solve_gen_full::apply(Mat<eT>& actual_out, const Base<eT,T1>& A_expr, const
      }
    else
      {
-      arma_warn(2, "solve(): system is singular (rcond: ", rcond, "); attempting approx solution");
+      arma_warn(2, "solve(): system is singular; rcond: ", rcond, "; attempting approx solution");
      }
    
    // TODO: conditionally recreate A: have a separate state flag which indicates whether A was previously overwritten
@@ -472,7 +472,7 @@ glue_solve_tri_default::apply(Mat<eT>& actual_out, const Base<eT,T1>& A_expr, co
      }
    else
      {
-      arma_warn(2, "solve(): system is singular (rcond: ", rcond, "); attempting approx solution");
+      arma_warn(2, "solve(): system is singular; rcond: ", rcond, "; attempting approx solution");
      }
    
    Mat<eT> triA = (triu) ? trimatu(A) : trimatl(A);  // trimatu() and trimatl() return the same type
@@ -598,7 +598,7 @@ glue_solve_tri_full::apply(Mat<eT>& actual_out, const Base<eT,T1>& A_expr, const
      }
    else
      {
-      arma_warn(2, "solve(): system is singular (rcond: ", rcond, "); attempting approx solution");
+      arma_warn(2, "solve(): system is singular; rcond: ", rcond, "; attempting approx solution");
      }
    
    Mat<eT> triA = (triu) ? trimatu(A) : trimatl(A);  // trimatu() and trimatl() return the same type
@@ -683,9 +683,9 @@ gmm_diag<eT>::learn
    || (seed_mode == random_subset)
    || (seed_mode == random_spread);
  
-  arma_conform_check( (dist_mode_ok == false), "gmm_diag::learn(): dist_mode must be eucl_dist or maha_dist" );
-  arma_conform_check( (seed_mode_ok == false), "gmm_diag::learn(): unknown seed_mode"                        );
-  arma_conform_check( (var_floor < eT(0)    ), "gmm_diag::learn(): variance floor is negative"               );
+  arma_conform_check( (dist_mode_ok         == false), "gmm_diag::learn(): dist_mode must be eucl_dist or maha_dist" );
+  arma_conform_check( (seed_mode_ok         == false), "gmm_diag::learn(): unknown seed_mode"                        );
+  arma_conform_check( ((var_floor >= eT(0)) == false), "gmm_diag::learn(): variance floor must be > 0"               );
  
  const unwrap<T1>   tmp_X(data.get_ref());
  const Mat<eT>& X = tmp_X.M;
@@ -722,9 +722,9 @@ gmm_full<eT>::learn
    || (seed_mode == random_subset)
    || (seed_mode == random_spread);
  
-  arma_conform_check( (dist_mode_ok == false), "gmm_full::learn(): dist_mode must be eucl_dist or maha_dist" );
-  arma_conform_check( (seed_mode_ok == false), "gmm_full::learn(): unknown seed_mode"                        );
-  arma_conform_check( (var_floor < eT(0)    ), "gmm_full::learn(): variance floor is negative"               );
+  arma_conform_check( (dist_mode_ok         == false), "gmm_full::learn(): dist_mode must be eucl_dist or maha_dist" );
+  arma_conform_check( (seed_mode_ok         == false), "gmm_full::learn(): unknown seed_mode"                        );
+  arma_conform_check( ((var_floor >= eT(0)) == false), "gmm_full::learn(): variance floor must be > 0"               );
  
  const unwrap<T1>   tmp_X(data.get_ref());
  const Mat<eT>& X = tmp_X.M;
@@ -77,8 +77,8 @@ SparseGenRealShiftSolve<eT>::SparseGenRealShiftSolve(const SpMat<eT>& mat_obj, c
    
    if( (x_rcond < std::numeric_limits<eT>::epsilon()) || arma_isnan(x_rcond) )
      {
-      if(x_rcond == eT(0))  { arma_warn(2, "matrix is singular to working precision");                        }
-      else                  { arma_warn(2, "matrix is singular to working precision (rcond: ", x_rcond, ")"); }
+      if(x_rcond == eT(0))  { arma_warn(2, "matrix is singular to working precision");                   }
+      else                  { arma_warn(2, "matrix is singular to working precision; rcond: ", x_rcond); }
      return;
      }
    
@@ -80,6 +80,8 @@ op_accu_mat::apply_proxy_at(const Proxy<T1>& P)
  const uword n_rows = P.get_n_rows();
  const uword n_cols = P.get_n_cols();
  
+  if(n_rows == 0)  { return eT(0); }
+  
  eT val = eT(0);
  
  if(n_rows != 1)
@@ -146,6 +148,8 @@ op_accu_mat::apply_omit_helper(const Proxy<T1>& P, functor is_omitted)
    const uword n_rows = P.get_n_rows();
    const uword n_cols = P.get_n_cols();
    
+    if(n_rows == 0)  { return eT_zero; }
+    
    for(uword c=0; c < n_cols; ++c)
    for(uword r=0; r < n_rows; ++r)
      {
@@ -602,6 +606,8 @@ op_accu_mat::apply(const subview<eT>& X)
  const uword X_n_rows = X.n_rows;
  const uword X_n_cols = X.n_cols;
  
+  if( (X_n_rows == 0) || (X_n_cols == 0) )  { return eT(0); }
+  
  if(X_n_rows == 1)
    {
    const uword X_m_n_rows = X.m.n_rows;
@@ -750,6 +756,8 @@ op_accu_cube::apply_proxy_at(const ProxyCube<T1>& P)
  const uword n_cols   = P.get_n_cols();
  const uword n_slices = P.get_n_slices();
  
+  if( (n_rows == 0) || (n_cols == 0) )  { return eT(0); }
+  
  eT val1 = eT(0);
  eT val2 = eT(0);
  
@@ -34,7 +34,7 @@ op_clamp::apply(Mat<typename T1::elem_type>& out, const mtOp<typename T1::elem_t
  const eT min_val = in.aux;
  const eT max_val = in.aux_out_eT;
  
-  arma_conform_check( (min_val > max_val), "clamp(): min_val must be less than max_val" );
+  arma_conform_check( ((min_val <= max_val) == false), "clamp(): min_val must be less than max_val" );
  
  if(is_Mat<T1>::value)
    {
@@ -83,7 +83,7 @@ op_clamp::apply(Mat_noalias<typename T1::elem_type>& out, const mtOp<typename T1
  const eT min_val = in.aux;
  const eT max_val = in.aux_out_eT;
  
-  arma_conform_check( (min_val > max_val), "clamp(): min_val must be less than max_val" );
+  arma_conform_check( ((min_val <= max_val) == false), "clamp(): min_val must be less than max_val" );
  
  if((quasi_unwrap<T1>::has_orig_mem) || (is_Mat<typename Proxy<T1>::stored_type>::value) || (arma_config::openmp && Proxy<T1>::use_mp))
    {
@@ -186,7 +186,7 @@ op_clamp::apply(Cube<typename T1::elem_type>& out, const mtOpCube<typename T1::e
  const eT min_val = in.aux;
  const eT max_val = in.aux_out_eT;
  
-  arma_conform_check( (min_val > max_val), "clamp(): min_val must be less than max_val" );
+  arma_conform_check( ((min_val <= max_val) == false), "clamp(): min_val must be less than max_val" );
  
  if(is_Cube<T1>::value)
    {
@@ -350,8 +350,8 @@ op_clamp_cx::apply_direct(Mat<eT>& out, const Mat<eT>& X, const eT min_val, cons
  const T max_val_real = std::real(max_val);
  const T max_val_imag = std::imag(max_val);
  
-  arma_conform_check( (min_val_real > max_val_real), "clamp(): real(min_val) must be less than real(max_val)" );
-  arma_conform_check( (min_val_imag > max_val_imag), "clamp(): imag(min_val) must be less than imag(max_val)" );
+  arma_conform_check( ((min_val_real <= max_val_real) == false), "clamp(): real(min_val) must be less than real(max_val)" );
+  arma_conform_check( ((min_val_imag <= max_val_imag) == false), "clamp(): imag(min_val) must be less than imag(max_val)" );
  
  if(&out != &X)
    {
@@ -401,8 +401,8 @@ op_clamp_cx::apply_proxy_noalias(Mat<typename T1::elem_type>& out, const Proxy<T
  const T max_val_real = std::real(max_val);
  const T max_val_imag = std::imag(max_val);
  
-  arma_conform_check( (min_val_real > max_val_real), "clamp(): real(min_val) must be less than real(max_val)" );
-  arma_conform_check( (min_val_imag > max_val_imag), "clamp(): imag(min_val) must be less than imag(max_val)" );
+  arma_conform_check( ((min_val_real <= max_val_real) == false), "clamp(): real(min_val) must be less than real(max_val)" );
+  arma_conform_check( ((min_val_imag <= max_val_imag) == false), "clamp(): imag(min_val) must be less than imag(max_val)" );
  
  const uword n_rows = P.get_n_rows();
  const uword n_cols = P.get_n_cols();
@@ -503,8 +503,8 @@ op_clamp_cx::apply_direct(Cube<eT>& out, const Cube<eT>& X, const eT min_val, co
  const T max_val_real = std::real(max_val);
  const T max_val_imag = std::imag(max_val);
  
-  arma_conform_check( (min_val_real > max_val_real), "clamp(): real(min_val) must be less than real(max_val)" );
-  arma_conform_check( (min_val_imag > max_val_imag), "clamp(): imag(min_val) must be less than imag(max_val)" );
+  arma_conform_check( ((min_val_real <= max_val_real) == false), "clamp(): real(min_val) must be less than real(max_val)" );
+  arma_conform_check( ((min_val_imag <= max_val_imag) == false), "clamp(): imag(min_val) must be less than imag(max_val)" );
  
  if(&out != &X)
    {
@@ -554,8 +554,8 @@ op_clamp_cx::apply_proxy_noalias(Cube<typename T1::elem_type>& out, const ProxyC
  const T max_val_real = std::real(max_val);
  const T max_val_imag = std::imag(max_val);
  
-  arma_conform_check( (min_val_real > max_val_real), "clamp(): real(min_val) must be less than real(max_val)" );
-  arma_conform_check( (min_val_imag > max_val_imag), "clamp(): imag(min_val) must be less than imag(max_val)" );
+  arma_conform_check( ((min_val_real <= max_val_real) == false), "clamp(): real(min_val) must be less than real(max_val)" );
+  arma_conform_check( ((min_val_imag <= max_val_imag) == false), "clamp(): imag(min_val) must be less than imag(max_val)" );
  
  const uword n_rows   = P.get_n_rows();
  const uword n_cols   = P.get_n_cols();
@@ -207,7 +207,7 @@ op_expmat_sym::apply_direct(Mat<typename T1::elem_type>& out, const Base<typenam
    
    if((arma_config::check_conform) && (arma_config::warn_level > 0) && (is_cx<eT>::yes) && (sym_helper::check_diag_imag(X) == false))
      {
-      arma_warn(1, "inv_sympd(): imaginary components on diagonal are non-zero");
+      arma_warn(1, "expmat_sym(): imaginary components on diagonal are non-zero");
      }
    
    if(is_op_diagmat<T1>::value || X.is_diagmat())
@@ -65,6 +65,7 @@ op_htrans::apply_mat_noalias(Mat<eT>& out, const Mat<eT>& A, const typename arma
    op_htrans::apply_mat_noalias_large(out, A);
    }
  else
+  if(A_n_cols != 0)
    {
    eT* outptr = out.memptr();
    
@@ -65,12 +65,18 @@ struct op_mean
  template<typename T1>
  inline static typename T1::elem_type mean_all(const T1& X);
  
+  template<typename T1>
+  inline static typename T1::elem_type mean_all_proxy(const Proxy<T1>& P);
+  
  template<typename T1>
  inline static typename T1::elem_type mean_all(const Op<T1, op_omit>& X);
  
  template<typename eT, typename functor>
  inline static eT mean_all_omit(const eT* X_mem, const uword N, functor is_omitted);
  
+  template<typename T1, typename functor>
+  inline static typename T1::elem_type mean_all_omit(const Proxy<T1>& P, functor is_omitted);
+  
  //
  
  template<typename eT>
@@ -435,17 +435,94 @@ op_mean::mean_all(const T1& X)
  arma_debug_sigprint();
  
  typedef typename T1::elem_type eT;
+  typedef typename T1::pod_type   T;
  
-  const quasi_unwrap<T1> U(X);
+  eT result = eT(0);
  
-  if(U.M.n_elem == 0)
+  if( (is_Mat<typename Proxy<T1>::stored_type>::value == false) && (Proxy<T1>::use_at == false) && (Proxy<T1>::use_mp == false) && (is_fp16<T>::no) )
    {
-    arma_conform_check(true, "mean(): object has no elements");
+    arma_debug_print("op_mean::mean_all(): using proxy");
    
-    return Datum<eT>::nan;
+    const Proxy<T1> P(X);
+    
+    if(P.get_n_elem() == 0)
+      {
+      arma_conform_check(true, "mean(): object has no elements");
+      
+      return Datum<eT>::nan;
+      }
+    
+    result = op_mean::mean_all_proxy(P);
+    }
+  else
+    {
+    arma_debug_print("op_mean::mean_all(): using quasi_unwrap");
+    
+    const quasi_unwrap<T1> U(X);
+    
+    if(U.M.n_elem == 0)
+      {
+      arma_conform_check(true, "mean(): object has no elements");
+      
+      return Datum<eT>::nan;
+      }
+    
+    result = op_mean::direct_mean(U.M.memptr(), U.M.n_elem);
    }
  
-  return op_mean::direct_mean(U.M.memptr(), U.M.n_elem);
+  return result;
+  }
+
+
+
+template<typename T1>
+inline
+typename T1::elem_type
+op_mean::mean_all_proxy(const Proxy<T1>& P)
+  {
+  arma_debug_sigprint();
+  
+  typedef typename T1::elem_type eT;
+  typedef typename T1::pod_type   T;
+  
+  const uword N = P.get_n_elem();
+  
+  const typename Proxy<T1>::ea_type Pea = P.get_ea();
+  
+  eT acc1 = eT(0);
+  eT acc2 = eT(0);
+  
+  uword i,j;
+  
+  for(i=0, j=1; j < N; i+=2, j+=2)
+    {
+    acc1 += Pea[i];
+    acc2 += Pea[j];
+    }
+  
+  if(i < N)
+    {
+    acc1 += Pea[i];
+    }
+  
+  const eT mean = (acc1 + acc2) / T(N);
+  
+  if(arma_isfinite(mean))  { return mean; }
+  
+  // handle possible overflow
+  
+  eT r_mean = eT(0);
+  
+  for(uword ii=0; ii < N; ++ii)
+    {
+    const eT val = Pea[ii];
+    
+    if(arma_isnonfinite(val))  { return mean; }
+    
+    r_mean = r_mean + (val - r_mean) / T(ii+1);
+    }
+  
+  return r_mean;
  }


@@ -467,22 +544,39 @@ op_mean::mean_all(const Op<T1, op_omit>& in)
    if(omit_mode == 2)  { arma_warn(1, "omit_nonfinite(): detection of non-finite values is not reliable in fast math mode"); }
    }
  
-  const quasi_unwrap<T1> U(in.m);
-  
-  if(U.M.n_elem == 0)
-    {
-    arma_conform_check(true, "mean(): object has no elements");
-    
-    return Datum<eT>::nan;
-    }
-  
  auto is_omitted_1 = [](const eT& x) -> bool { return arma_isnan(x);       };
  auto is_omitted_2 = [](const eT& x) -> bool { return arma_isnonfinite(x); };
  
  eT result = eT(0);
  
-  if(omit_mode == 1)  { result = op_mean::mean_all_omit(U.M.memptr(), U.M.n_elem, is_omitted_1); }
-  if(omit_mode == 2)  { result = op_mean::mean_all_omit(U.M.memptr(), U.M.n_elem, is_omitted_2); }
+  if( (is_Mat<typename Proxy<T1>::stored_type>::value == false) && (Proxy<T1>::use_at == false) && (Proxy<T1>::use_mp == false) )
+    {
+    const Proxy<T1> P(in.m);
+    
+    if(P.get_n_elem() == 0)
+      {
+      arma_conform_check(true, "mean(): object has no elements");
+      
+      return Datum<eT>::nan;
+      }
+    
+    if(omit_mode == 1)  { result = op_mean::mean_all_omit(P, is_omitted_1); }
+    if(omit_mode == 2)  { result = op_mean::mean_all_omit(P, is_omitted_2); }
+    }
+  else
+    {
+    const quasi_unwrap<T1> U(in.m);
+    
+    if(U.M.n_elem == 0)
+      {
+      arma_conform_check(true, "mean(): object has no elements");
+      
+      return Datum<eT>::nan;
+      }
+    
+    if(omit_mode == 1)  { result = op_mean::mean_all_omit(U.M.memptr(), U.M.n_elem, is_omitted_1); }
+    if(omit_mode == 2)  { result = op_mean::mean_all_omit(U.M.memptr(), U.M.n_elem, is_omitted_2); }
+    }
  
  return result;
  }
@@ -535,6 +629,55 @@ op_mean::mean_all_omit(const eT* X_mem, const uword N, functor is_omitted)



+template<typename T1, typename functor>
+inline
+typename T1::elem_type
+op_mean::mean_all_omit(const Proxy<T1>& P, functor is_omitted)
+  {
+  arma_debug_sigprint();
+  
+  typedef typename T1::elem_type eT;
+  typedef typename T1::pod_type   T;
+  
+  const uword N = P.get_n_elem();
+  
+  uword count = 0;
+  eT    acc   = eT(0);
+  
+  for(uword i=0; i < N; ++i)
+    {
+    const eT val = P[i];
+    
+    if(is_omitted(val) == false)  { acc += val; ++count; }
+    }
+  
+  acc /= T(count);
+  
+  if(arma_isfinite(acc))  { return acc; }
+  
+  // handle possible overflow
+  
+  eT r_mean = eT(0);
+  
+  count = 0;
+  
+  for(uword i=0; i < N; ++i)
+    {
+    const eT val = P[i];
+    
+    if(is_omitted(val) == false)
+      {
+      r_mean = r_mean + (val - r_mean) / T(count+1);  // kept as count+1 to use same algorithm as op_mean::direct_mean_robust()
+      
+      ++count;
+      }
+    }
+  
+  return r_mean;
+  }
+
+
+
 //


@@ -110,8 +110,8 @@ op_norm2est::norm2est
  typedef typename T1::pod_type   T;
  typedef typename T1::elem_type eT;
  
-  arma_conform_check( (tolerance <      T(0)), "norm2est(): parameter 'tolerance' must be > 0" );
-  arma_conform_check( (max_iter  == uword(0)), "norm2est(): parameter 'max_iter' must be > 0"  );
+  arma_conform_check( ((tolerance >= T(0)) == false), "norm2est(): parameter 'tolerance' must be > 0" );
+  arma_conform_check( (max_iter == uword(0)),         "norm2est(): parameter 'max_iter' must be > 0"  );
  
  const T tol = (tolerance == T(0)) ? T(1e-6) : T(tolerance);
  
@@ -190,8 +190,8 @@ op_norm2est::norm2est
  typedef typename T1::pod_type   T;
  typedef typename T1::elem_type eT;
  
-  arma_conform_check( (tolerance <      T(0)), "norm2est(): parameter 'tolerance' must be > 0" );
-  arma_conform_check( (max_iter  == uword(0)), "norm2est(): parameter 'max_iter' must be > 0"  );
+  arma_conform_check( ((tolerance >= T(0)) == false), "norm2est(): parameter 'tolerance' must be > 0" );
+  arma_conform_check( (max_iter == uword(0)),         "norm2est(): parameter 'max_iter' must be > 0"  );
  
  const T tol = (tolerance == T(0)) ? T(1e-6) : T(tolerance);
  
@@ -54,7 +54,7 @@ op_orth::apply_direct(Mat<typename T1::elem_type>& out, const Base<typename T1::
  typedef typename T1::elem_type eT;
  typedef typename T1::pod_type   T;
  
-  arma_conform_check((tol < T(0)), "orth(): tolerance must be >= 0");
+  arma_conform_check( ((tol >= T(0)) == false), "orth(): tolerance must be > 0" );
  
  Mat<eT> U;
  Col< T> s;
@@ -87,6 +87,8 @@ op_orth::apply_direct(Mat<typename T1::elem_type>& out, const Base<typename T1::
  // set tolerance to default if it hasn't been specified
  if(tol == T(0))  { tol = (std::max)(A.n_rows, A.n_cols) * s_mem[0] * std::numeric_limits<T>::epsilon(); }
  
+  if(arma_isnan(tol))  { return false; }
+  
  uword count = 0;
  
  for(uword i=0; i < s_n_elem; ++i)  { count += (s_mem[i] > tol) ? uword(1) : uword(0); }
@@ -141,7 +143,7 @@ op_null::apply_direct(Mat<typename T1::elem_type>& out, const Base<typename T1::
  typedef typename T1::elem_type eT;
  typedef typename T1::pod_type   T;
  
-  arma_conform_check((tol < T(0)), "null(): tolerance must be >= 0");
+  arma_conform_check( ((tol >= T(0)) == false), "null(): tolerance must be > 0" );
  
  Mat<eT> U;
  Col< T> s;
@@ -174,6 +176,8 @@ op_null::apply_direct(Mat<typename T1::elem_type>& out, const Base<typename T1::
  // set tolerance to default if it hasn't been specified
  if(tol == T(0))  { tol = (std::max)(A.n_rows, A.n_cols) * s_mem[0] * std::numeric_limits<T>::epsilon(); }
  
+  if(arma_isnan(tol))  { return false; }
+  
  uword count = 0;
  
  for(uword i=0; i < s_n_elem; ++i)  { count += (s_mem[i] > tol) ? uword(1) : uword(0); }
@@ -94,7 +94,7 @@ op_pinv::apply_direct(Mat<typename T1::elem_type>& out, const Base<typename T1::
  typedef typename T1::elem_type eT;
  typedef typename T1::pod_type   T;
  
-  arma_conform_check((tol < T(0)), "pinv(): tolerance must be >= 0");
+  arma_conform_check( ((tol >= T(0)) == false), "pinv(): tolerance must be > 0" );
  
  // method_id = 0 -> default setting
  // method_id = 1 -> use standard algorithm
@@ -176,6 +176,8 @@ op_pinv::apply_diag(Mat<eT>& out, const Mat<eT>& A, typename get_pod_type<eT>::r
  
  if(tol == T(0))  { tol = (std::max)(A.n_rows, A.n_cols) * max_abs_Aii * std::numeric_limits<T>::epsilon(); }
  
+  if(arma_isnan(tol))  { return false; }
+  
  for(uword i=0; i<N; ++i)
    {
    if(diag_abs_vals[i] >= tol)
@@ -236,6 +238,8 @@ op_pinv::apply_sym(Mat<eT>& out, const Mat<eT>& A, typename get_pod_type<eT>::re
  // set tolerance to default if it hasn't been specified
  if(tol == T(0))  { tol = (std::max)(A.n_rows, A.n_cols) * abs_eigval[0] * std::numeric_limits<T>::epsilon(); }
  
+  if(arma_isnan(tol))  { return false; }
+  
  uword count = 0;
  
  for(uword i=0; i < abs_eigval.n_elem; ++i)  { count += (abs_eigval[i] >= tol) ? uword(1) : uword(0); }
@@ -310,6 +314,8 @@ op_pinv::apply_gen(Mat<eT>& out, Mat<eT>& A, typename get_pod_type<eT>::result t
  // set tolerance to default if it hasn't been specified
  if( (tol == T(0)) && (s.n_elem > 0) )  { tol = (std::max)(n_rows, n_cols) * s[0] * std::numeric_limits<T>::epsilon(); }
  
+  if(arma_isnan(tol))  { return false; }
+  
  uword count = 0;
  
  for(uword i=0; i < s.n_elem; ++i)  { count += (s[i] >= tol) ? uword(1) : uword(0); }
@@ -87,6 +87,8 @@ op_rank::apply_diag(uword& out, Mat<eT>& A, typename get_pod_type<eT>::result to
  
  typedef typename get_pod_type<eT>::result T;
  
+  out = uword(0);
+  
  const uword N = (std::min)(A.n_rows, A.n_cols);
  
  podarray<T> diag_abs_vals(N);
@@ -98,7 +100,7 @@ op_rank::apply_diag(uword& out, Mat<eT>& A, typename get_pod_type<eT>::result to
    const eT     Aii = A.at(i,i);
    const  T abs_Aii = std::abs(Aii);
    
-    if(arma_isnan(Aii))  { out = uword(0); return false; }
+    if(arma_isnan(Aii))  { return false; }
    
    diag_abs_vals[i] = abs_Aii;
    
@@ -108,6 +110,8 @@ op_rank::apply_diag(uword& out, Mat<eT>& A, typename get_pod_type<eT>::result to
  // set tolerance to default if it hasn't been specified
  if(tol == T(0))  { tol = (std::max)(A.n_rows, A.n_cols) * max_abs_Aii * std::numeric_limits<T>::epsilon(); }
  
+  if(arma_isnan(tol))  { return false; }
+  
  uword count = 0;
  
  for(uword i=0; i<N; ++i)  { count += (diag_abs_vals[i] > tol) ? uword(1) : uword(0); }
@@ -128,18 +132,20 @@ op_rank::apply_sym(uword& out, Mat<eT>& A, typename get_pod_type<eT>::result tol
  
  typedef typename get_pod_type<eT>::result T;
  
-  if(A.is_square() == false)  { out = uword(0); return false; }
+  out = uword(0);
+  
+  if(A.is_square() == false)  { return false; }
  
  Col<T> v;
  
  const bool status = auxlib::eig_sym(v, A);
  
-  if(status == false)  { out = uword(0); return false; }
+  if(status == false)  { return false; }
  
  const uword v_n_elem = v.n_elem;
        T*    v_mem    = v.memptr();
  
-  if(v_n_elem == 0)  { out = uword(0); return true; }
+  if(v_n_elem == 0)  { return true; }
  
  T max_abs_v = T(0);
  
@@ -148,6 +154,8 @@ op_rank::apply_sym(uword& out, Mat<eT>& A, typename get_pod_type<eT>::result tol
  // set tolerance to default if it hasn't been specified
  if(tol == T(0))  { tol = (std::max)(A.n_rows, A.n_cols) * max_abs_v * std::numeric_limits<T>::epsilon(); }
  
+  if(arma_isnan(tol))  { return false; }
+  
  uword count = 0;
  
  for(uword i=0; i < v_n_elem; ++i)  { count += (v_mem[i] > tol) ? uword(1) : uword(0); }
@@ -168,20 +176,24 @@ op_rank::apply_gen(uword& out, Mat<eT>& A, typename get_pod_type<eT>::result tol
  
  typedef typename get_pod_type<eT>::result T;
  
+  out = uword(0);
+  
  Col<T> s;
  
  const bool status = auxlib::svd_dc(s, A);
  
-  if(status == false)  { out = uword(0); return false; }
+  if(status == false)  { return false; }
  
  const uword s_n_elem = s.n_elem;
  const T*    s_mem    = s.memptr();
  
-  if(s_n_elem == 0)  { out = uword(0); return true; }
+  if(s_n_elem == 0)  { return true; }
  
  // set tolerance to default if it hasn't been specified
  if(tol == T(0))  { tol = (std::max)(A.n_rows, A.n_cols) * s_mem[0] * std::numeric_limits<T>::epsilon(); }
  
+  if(arma_isnan(tol))  { return false; }
+  
  uword count = 0;
  
  for(uword i=0; i < s_n_elem; ++i)  { count += (s_mem[i] > tol) ? uword(1) : uword(0); }
@@ -200,6 +200,7 @@ op_strans::apply_mat_noalias(Mat<eT>& out, const TA& A)
      op_strans::apply_mat_noalias_large(out, A);
      }
    else
+    if(A_n_cols != 0)
      {
      eT* outptr = out.memptr();
      
@@ -176,6 +176,8 @@ op_vectorise_col::apply_subview(Mat<eT>& out, const subview<eT>& sv)
  
  out.set_size(sv.n_elem, 1);
  
+  if(sv.n_elem == 0)  { return; }
+  
  eT* out_mem = out.memptr();
  
  for(uword col=0; col < sv_n_cols; ++col)
@@ -201,6 +203,8 @@ op_vectorise_col::apply_proxy(Mat<typename T1::elem_type>& out, const Proxy<T1>&
  
  out.set_size(N, 1);
  
+  if(N == 0)  { return; }
+  
  eT* outmem = out.memptr();
  
  if(Proxy<T1>::use_at == false)
@@ -305,6 +309,8 @@ op_vectorise_row::apply_proxy(Mat<typename T1::elem_type>& out, const Proxy<T1>&
  
  out.set_size(1, n_elem);
  
+  if(n_elem == 0)  { return; }
+  
  eT* outmem = out.memptr();
  
  if(n_cols == 1)
@@ -471,6 +477,8 @@ op_vectorise_cube_col::apply_proxy(Mat<typename T1::elem_type>& out, const T1& e
  
  out.set_size(N, 1);
  
+  if(N == 0)  { return; }
+  
  eT* outmem = out.memptr();
  
  if(ProxyCube<T1>::use_at == false)
@@ -113,7 +113,7 @@ op_wishrnd::apply_noalias_mode2(Mat<eT>& out, const Mat<eT>& D, const eT df)
  {
  arma_debug_sigprint();
  
-  arma_conform_check( (df <= eT(0)),            "df must be greater than zero"                 );
+  arma_conform_check( ((df > eT(0))  == false), "df must be greater than zero"                 );
  arma_conform_check( (D.is_square() == false), "wishrnd(): given matrix must be square sized" );
  
  if(D.is_empty())  { out.reset(); return true; }
@@ -256,7 +256,7 @@ op_iwishrnd::apply_noalias_mode2(Mat<eT>& out, const Mat<eT>& Dinv, const eT df)
  {
  arma_debug_sigprint();
  
-  arma_conform_check( (df <= eT(0)),               "df must be greater than zero"                  );
+  arma_conform_check( ((df > eT(0))     == false), "df must be greater than zero"                  );
  arma_conform_check( (Dinv.is_square() == false), "iwishrnd(): given matrix must be square sized" );
  
  if(Dinv.is_empty())  { out.reset(); return true; }
@@ -214,6 +214,8 @@ sp_auxlib::eigs_sym_newarp(Col<eT>& eigval, Mat<eT>& eigvec, const SpMat<eT>& X,
    if(ncv < (n_eigvals + 1)) { ncv = (n_eigvals + 1); }
    if(ncv > n              ) { ncv = n;               }
    
+    if(arma_isnan(opts.tol))  { return false; }
+    
    eT tol = (std::max)(eT(opts.tol), std::numeric_limits<eT>::epsilon());
    
    uword maxiter = uword(opts.maxiter);
@@ -347,6 +349,8 @@ sp_auxlib::eigs_sym_newarp(Col<eT>& eigval, Mat<eT>& eigvec, const SpMat<eT>& X,
    if(ncv < (n_eigvals + 1)) { ncv = (n_eigvals + 1); }
    if(ncv > n              ) { ncv = n;               }
    
+    if(arma_isnan(opts.tol))  { return false; }
+    
    eT tol = (std::max)(eT(opts.tol), std::numeric_limits<eT>::epsilon());
    
    uword maxiter = uword(opts.maxiter);
@@ -503,7 +507,7 @@ sp_auxlib::eigs_sym_arpack(Col<eT>& eigval, Mat<eT>& eigvec, const SpMat<eT>& X,
    arpack::seupd(&rvec, &howmny, select.memptr(), eigval.memptr(), eigvec.memptr(), &ldz, (eT*) &sigma, &bmat, &n, which, &nev, &tol, resid.memptr(), &ncv, v.memptr(), &ldv, iparam.memptr(), ipntr.memptr(), workd.memptr(), workl.memptr(), &lworkl, &info);
    
    // Check for errors.
-    if(info != 0)  { arma_warn(1, "eigs_sym(): ARPACK error ", info, " in seupd()"); return false; }
+    if(info != 0)  { arma_warn(1, "eigs_sym(): arpack::seupd() error: ", info); return false; }
    
    return (info == 0);
    }
@@ -667,6 +671,8 @@ sp_auxlib::eigs_gen_newarp(Col< std::complex<T> >& eigval, Mat< std::complex<T>
    if(ncv < (n_eigvals + 3)) { ncv = (n_eigvals + 3); }
    if(ncv > n              ) { ncv = n;               }
    
+    if(arma_isnan(opts.tol))  { return false; }
+    
    T tol = (std::max)(T(opts.tol), std::numeric_limits<T>::epsilon());
    
    uword maxiter = uword(opts.maxiter);
@@ -890,7 +896,7 @@ sp_auxlib::eigs_gen_arpack(Col< std::complex<T> >& eigval, Mat< std::complex<T>
    arpack::neupd(&rvec, &howmny, select.memptr(), dr.memptr(), di.memptr(), z.memptr(), &ldz, (T*) &sigmar, (T*) &sigmai, workev.memptr(), &bmat, &n, which, &nev, &tol, resid.memptr(), &ncv, v.memptr(), &ldv, iparam.memptr(), ipntr.memptr(), workd.memptr(), workl.memptr(), &lworkl, rwork.memptr(), &info);
    
    // Check for errors.
-    if(info != 0)  { arma_warn(1, "eigs_gen(): ARPACK error ", info, " in neupd()"); return false; }
+    if(info != 0)  { arma_warn(1, "eigs_gen(): arpack::neupd() error: ", info); return false; }
    
    // Put it into the outputs.
    eigval.set_size(n_eigvals);
@@ -1138,7 +1144,7 @@ sp_auxlib::eigs_gen(Col< std::complex<T> >& eigval, Mat< std::complex<T> >& eigv
 (std::complex<T>*) NULL, eigvec.memptr(), &ldz, (std::complex<T>*) &sigma, (std::complex<T>*) NULL, workev.memptr(), &bmat, &n, which, &nev, &tol, resid.memptr(), &ncv, v.memptr(), &ldv, iparam.memptr(), ipntr.memptr(), workd.memptr(), workl.memptr(), &lworkl, rwork.memptr(), &info);
    
    // Check for errors.
-    if(info != 0)  { arma_warn(1, "eigs_gen(): ARPACK error ", info, " in neupd()"); return false; }
+    if(info != 0)  { arma_warn(1, "eigs_gen(): arpack::neupd() error: ", info); return false; }
    
    return (info == 0);
    }
@@ -1258,7 +1264,7 @@ sp_auxlib::spsolve_simple(Mat<typename T1::elem_type>& X, const SpBase<typename
    else
    if(info < 0)
      {
-      arma_warn(1, "spsolve(): unknown SuperLU error code from gssv(): ", info);
+      arma_warn(1, "spsolve(): superlu::gssv() error: ", info);
      }
    
    // No need to extract the data from x, since it's using the same memory as X
@@ -1406,7 +1412,7 @@ sp_auxlib::spsolve_refine(Mat<typename T1::elem_type>& X, typename T1::pod_type&
    else
    if( (info == superlu::int_t(A.n_cols+1)) && (user_opts.allow_ugly) )
      {
-      arma_warn(2, "spsolve(): system is singular to working precision (rcond: ", rcond, ")");
+      arma_warn(2, "spsolve(): system is singular to working precision; rcond: ", rcond);
      status = true;
      }
    else
@@ -1417,7 +1423,7 @@ sp_auxlib::spsolve_refine(Mat<typename T1::elem_type>& X, typename T1::pod_type&
    else
    if(info < 0)
      {
-      arma_warn(1, "spsolve(): unknown SuperLU error code from gssvx(): ", info);
+      arma_warn(1, "spsolve(): superlu::gssvx() error: ", info);
      }
    
    // No need to extract the data from x, since it's using the same memory as X
@@ -2013,11 +2019,11 @@ sp_auxlib::run_aupd_plain
      
      if(sym)
        {
-        arma_warn(1, "eigs_sym(): ARPACK error ", info, " in saupd()");
+        arma_warn(1, "eigs_sym(): arpack::saupd() error: ", info);
        }
      else
        {
-        arma_warn(1, "eigs_gen(): ARPACK error ", info, " in naupd()");
+        arma_warn(1, "eigs_gen(): arpack::naupd() error: ", info);
        }
      
      return; // Parent frame can look at the value of info.
@@ -2200,7 +2206,7 @@ sp_auxlib::run_aupd_shiftinvert
    
    if( (x_rcond < std::numeric_limits<eT>::epsilon()) || arma_isnan(x_rcond) )
      {
-      arma_warn(2, "matrix is singular to working precision (rcond: ", x_rcond, ")");
+      arma_warn(2, "matrix is singular to working precision; rcond: ", x_rcond);
      info = blas_int(-1);
      return;
      }
@@ -2270,11 +2276,11 @@ sp_auxlib::run_aupd_shiftinvert
      
      if(sym)
        {
-        arma_warn(2, "eigs_sym(): ARPACK error ", info, " in saupd()");
+        arma_warn(2, "eigs_sym(): arpack::saupd() error: ", info);
        }
      else
        {
-        arma_warn(2, "eigs_gen(): ARPACK error ", info, " in naupd()");
+        arma_warn(2, "eigs_gen(): arpack::naupd() error: ", info);
        }
      
      return; // Parent frame can look at the value of info.
@@ -923,7 +923,7 @@ spdiagview<eT>::clamp(const eT min_val, const eT max_val)
  {
  arma_debug_sigprint();
  
-  SpMat<eT> tmp(*this);
+  Mat<eT> tmp(*this);
  
  tmp.clamp(min_val, max_val);
  
@@ -142,6 +142,9 @@ class subview : public Base< eT, subview<eT> >
  arma_inline       eT* colptr(const uword in_col);
  arma_inline const eT* colptr(const uword in_col) const;
  
+  arma_inline       eT* startptr();
+  arma_inline const eT* startptr() const;
+  
  template<typename eT2>
  inline bool check_overlap(const subview<eT2>& x) const;
  
@@ -392,11 +395,16 @@ class subview_col : public subview<eT>
  
  arma_warn_unused arma_inline const Op<subview_col<eT>,op_strans> as_row() const;
  
+  inline void replace(const eT old_val, const eT new_val);
+  
  inline void fill(const eT val);
  inline void zeros();
  inline void ones();
+  inline void randu();
+  inline void randn();
  
  arma_warn_unused inline bool is_finite() const;
+  arma_warn_unused inline bool is_zero(const pod_type tol = 0) const;
  
  arma_warn_unused inline bool has_inf() const;
  arma_warn_unused inline bool has_nan() const;
@@ -552,11 +560,16 @@ class subview_row : public subview<eT>
  
  arma_warn_unused arma_inline const Op<subview_row<eT>,op_strans> as_col() const;
  
+  inline void replace(const eT old_val, const eT new_val);
+  
  inline void fill(const eT val);
  inline void zeros();
  inline void ones();
+  inline void randu();
+  inline void randn();
  
  arma_warn_unused inline bool is_finite() const;
+  arma_warn_unused inline bool is_zero(const pod_type tol = 0) const;
  
  arma_warn_unused inline bool has_inf() const;
  arma_warn_unused inline bool has_nan() const;
@@ -109,6 +109,8 @@ subview_cube_each1<eT>::operator= (const Base<eT,T1>& in)
  const uword p_n_slices     = p.n_slices;
  const uword p_n_elem_slice = p.n_elem_slice;
  
+  if(p_n_elem_slice == 0)  { return; }
+  
  const eT* A_mem = A.memptr();
  
  for(uword i=0; i < p_n_slices; ++i)  { arrayops::copy( p.slice_memptr(i), A_mem, p_n_elem_slice ); }
@@ -134,6 +136,8 @@ subview_cube_each1<eT>::operator+= (const Base<eT,T1>& in)
  const uword p_n_slices     = p.n_slices;
  const uword p_n_elem_slice = p.n_elem_slice;
  
+  if(p_n_elem_slice == 0)  { return; }
+  
  const eT* A_mem = A.memptr();
  
  for(uword i=0; i < p_n_slices; ++i)  { arrayops::inplace_plus( p.slice_memptr(i), A_mem, p_n_elem_slice ); }
@@ -159,6 +163,8 @@ subview_cube_each1<eT>::operator-= (const Base<eT,T1>& in)
  const uword p_n_slices     = p.n_slices;
  const uword p_n_elem_slice = p.n_elem_slice;
  
+  if(p_n_elem_slice == 0)  { return; }
+  
  const eT* A_mem = A.memptr();
  
  for(uword i=0; i < p_n_slices; ++i)  { arrayops::inplace_minus( p.slice_memptr(i), A_mem, p_n_elem_slice ); }
@@ -184,6 +190,8 @@ subview_cube_each1<eT>::operator%= (const Base<eT,T1>& in)
  const uword p_n_slices     = p.n_slices;
  const uword p_n_elem_slice = p.n_elem_slice;
  
+  if(p_n_elem_slice == 0)  { return; }
+  
  const eT* A_mem = A.memptr();
  
  for(uword i=0; i < p_n_slices; ++i)  { arrayops::inplace_mul( p.slice_memptr(i), A_mem, p_n_elem_slice ); }
@@ -209,6 +217,8 @@ subview_cube_each1<eT>::operator/= (const Base<eT,T1>& in)
  const uword p_n_slices     = p.n_slices;
  const uword p_n_elem_slice = p.n_elem_slice;
  
+  if(p_n_elem_slice == 0)  { return; }
+  
  const eT* A_mem = A.memptr();
  
  for(uword i=0; i < p_n_slices; ++i)  { arrayops::inplace_div( p.slice_memptr(i), A_mem, p_n_elem_slice ); }
@@ -300,6 +310,8 @@ subview_cube_each2<eT,TB>::operator= (const Base<eT,T1>& in)
    
    arma_conform_check_bounds( (slice >= p_n_slices), "each_slice(): index out of bounds" );
    
+    if(p_n_elem_slice == 0)  { continue; }
+    
    arrayops::copy(p.slice_memptr(slice), A_mem, p_n_elem_slice);
    }
  }
@@ -339,6 +351,8 @@ subview_cube_each2<eT,TB>::operator+= (const Base<eT,T1>& in)
    
    arma_conform_check_bounds( (slice >= p_n_slices), "each_slice(): index out of bounds" );
    
+    if(p_n_elem_slice == 0)  { continue; }
+    
    arrayops::inplace_plus(p.slice_memptr(slice), A_mem, p_n_elem_slice);
    }
  }
@@ -378,6 +392,8 @@ subview_cube_each2<eT,TB>::operator-= (const Base<eT,T1>& in)
    
    arma_conform_check_bounds( (slice >= p_n_slices), "each_slice(): index out of bounds" );
    
+    if(p_n_elem_slice == 0)  { continue; }
+    
    arrayops::inplace_minus(p.slice_memptr(slice), A_mem, p_n_elem_slice);
    }
  }
@@ -417,6 +433,8 @@ subview_cube_each2<eT,TB>::operator%= (const Base<eT,T1>& in)
    
    arma_conform_check_bounds( (slice >= p_n_slices), "each_slice(): index out of bounds" );
    
+    if(p_n_elem_slice == 0)  { continue; }
+    
    arrayops::inplace_mul(p.slice_memptr(slice), A_mem, p_n_elem_slice);
    }
  }
@@ -456,6 +474,8 @@ subview_cube_each2<eT,TB>::operator/= (const Base<eT,T1>& in)
    
    arma_conform_check_bounds( (slice >= p_n_slices), "each_slice(): index out of bounds" );
    
+    if(p_n_elem_slice == 0)  { continue; }
+    
    arrayops::inplace_div(p.slice_memptr(slice), A_mem, p_n_elem_slice);
    }
  }
@@ -492,12 +512,15 @@ subview_cube_each1_aux::operator_plus
  
  X.check_size(A);
  
-  for(uword i=0; i < p_n_slices; ++i)
+  if( (p_n_rows != 0) && (p_n_cols != 0) )
    {
-          Mat<eT> out_slice(              out.slice_memptr(i),  p_n_rows, p_n_cols, false, true);
-    const Mat<eT>   p_slice(const_cast<eT*>(p.slice_memptr(i)), p_n_rows, p_n_cols, false, true);
-    
-    out_slice = p_slice + A;
+    for(uword i=0; i < p_n_slices; ++i)
+      {
+            Mat<eT> out_slice(              out.slice_memptr(i),  p_n_rows, p_n_cols, false, true);
+      const Mat<eT>   p_slice(const_cast<eT*>(p.slice_memptr(i)), p_n_rows, p_n_cols, false, true);
+      
+      out_slice = p_slice + A;
+      }
    }
  
  return out;
@@ -529,12 +552,15 @@ subview_cube_each1_aux::operator_minus
  
  X.check_size(A);
  
-  for(uword i=0; i < p_n_slices; ++i)
+  if( (p_n_rows != 0) && (p_n_cols != 0) )
    {
-          Mat<eT> out_slice(              out.slice_memptr(i),  p_n_rows, p_n_cols, false, true);
-    const Mat<eT>   p_slice(const_cast<eT*>(p.slice_memptr(i)), p_n_rows, p_n_cols, false, true);
-    
-    out_slice = p_slice - A;
+    for(uword i=0; i < p_n_slices; ++i)
+      {
+            Mat<eT> out_slice(              out.slice_memptr(i),  p_n_rows, p_n_cols, false, true);
+      const Mat<eT>   p_slice(const_cast<eT*>(p.slice_memptr(i)), p_n_rows, p_n_cols, false, true);
+      
+      out_slice = p_slice - A;
+      }
    }
  
  return out;
@@ -566,12 +592,15 @@ subview_cube_each1_aux::operator_minus
  
  Y.check_size(A);
  
-  for(uword i=0; i < p_n_slices; ++i)
+  if( (p_n_rows != 0) && (p_n_cols != 0) )
    {
-          Mat<eT> out_slice(              out.slice_memptr(i),  p_n_rows, p_n_cols, false, true);
-    const Mat<eT>   p_slice(const_cast<eT*>(p.slice_memptr(i)), p_n_rows, p_n_cols, false, true);
-    
-    out_slice = A - p_slice;
+    for(uword i=0; i < p_n_slices; ++i)
+      {
+            Mat<eT> out_slice(              out.slice_memptr(i),  p_n_rows, p_n_cols, false, true);
+      const Mat<eT>   p_slice(const_cast<eT*>(p.slice_memptr(i)), p_n_rows, p_n_cols, false, true);
+      
+      out_slice = A - p_slice;
+      }
    }
  
  return out;
@@ -603,12 +632,15 @@ subview_cube_each1_aux::operator_schur
  
  X.check_size(A);
  
-  for(uword i=0; i < p_n_slices; ++i)
+  if( (p_n_rows != 0) && (p_n_cols != 0) )
    {
-          Mat<eT> out_slice(              out.slice_memptr(i),  p_n_rows, p_n_cols, false, true);
-    const Mat<eT>   p_slice(const_cast<eT*>(p.slice_memptr(i)), p_n_rows, p_n_cols, false, true);
-    
-    out_slice = p_slice % A;
+    for(uword i=0; i < p_n_slices; ++i)
+      {
+            Mat<eT> out_slice(              out.slice_memptr(i),  p_n_rows, p_n_cols, false, true);
+      const Mat<eT>   p_slice(const_cast<eT*>(p.slice_memptr(i)), p_n_rows, p_n_cols, false, true);
+      
+      out_slice = p_slice % A;
+      }
    }
  
  return out;
@@ -640,12 +672,15 @@ subview_cube_each1_aux::operator_div
  
  X.check_size(A);
  
-  for(uword i=0; i < p_n_slices; ++i)
+  if( (p_n_rows != 0) && (p_n_cols != 0) )
    {
-          Mat<eT> out_slice(              out.slice_memptr(i),  p_n_rows, p_n_cols, false, true);
-    const Mat<eT>   p_slice(const_cast<eT*>(p.slice_memptr(i)), p_n_rows, p_n_cols, false, true);
-    
-    out_slice = p_slice / A;
+    for(uword i=0; i < p_n_slices; ++i)
+      {
+            Mat<eT> out_slice(              out.slice_memptr(i),  p_n_rows, p_n_cols, false, true);
+      const Mat<eT>   p_slice(const_cast<eT*>(p.slice_memptr(i)), p_n_rows, p_n_cols, false, true);
+      
+      out_slice = p_slice / A;
+      }
    }
  
  return out;
@@ -677,12 +712,15 @@ subview_cube_each1_aux::operator_div
  
  Y.check_size(A);
  
-  for(uword i=0; i < p_n_slices; ++i)
+  if( (p_n_rows != 0) && (p_n_cols != 0) )
    {
-          Mat<eT> out_slice(              out.slice_memptr(i),  p_n_rows, p_n_cols, false, true);
-    const Mat<eT>   p_slice(const_cast<eT*>(p.slice_memptr(i)), p_n_rows, p_n_cols, false, true);
-    
-    out_slice = A / p_slice;
+    for(uword i=0; i < p_n_slices; ++i)
+      {
+            Mat<eT> out_slice(              out.slice_memptr(i),  p_n_rows, p_n_cols, false, true);
+      const Mat<eT>   p_slice(const_cast<eT*>(p.slice_memptr(i)), p_n_rows, p_n_cols, false, true);
+      
+      out_slice = A / p_slice;
+      }
    }
  
  return out;
@@ -706,14 +744,26 @@ subview_cube_each1_aux::operator_times
  const unwrap<T2>   tmp(Y.get_ref());
  const Mat<eT>& M = tmp.M;
  
+  if(arma_config::check_conform)
+    {
+    if(C.n_cols != M.n_rows)  { arma_stop_logic_error("each_slice(): incompatible sizes for matrix multiplication"); }
+    }
+  
  Cube<eT> out(C.n_rows, M.n_cols, C.n_slices, arma_nozeros_indicator());
  
-  for(uword i=0; i < C.n_slices; ++i)
+  if( (C.n_elem == 0) || (M.n_elem == 0) )
    {
-          Mat<eT> out_slice(              out.slice_memptr(i),  C.n_rows, M.n_cols, false, true);
-    const Mat<eT>   C_slice(const_cast<eT*>(C.slice_memptr(i)), C.n_rows, C.n_cols, false, true);
-    
-    out_slice = C_slice * M;
+    out.zeros();
+    }
+  else
+    {
+    for(uword i=0; i < C.n_slices; ++i)
+      {
+            Mat<eT> out_slice(              out.slice_memptr(i),  C.n_rows, M.n_cols, false, true);
+      const Mat<eT>   C_slice(const_cast<eT*>(C.slice_memptr(i)), C.n_rows, C.n_cols, false, true);
+      
+      out_slice = C_slice * M;
+      }
    }
  
  return out;
@@ -737,14 +787,26 @@ subview_cube_each1_aux::operator_times
  
  const Cube<eT>& C = Y.P;
  
+  if(arma_config::check_conform)
+    {
+    if(M.n_cols != C.n_rows)  { arma_stop_logic_error("each_slice(): incompatible sizes for matrix multiplication"); }
+    }
+  
  Cube<eT> out(M.n_rows, C.n_cols, C.n_slices, arma_nozeros_indicator());
  
-  for(uword i=0; i < C.n_slices; ++i)
+  if( (M.n_elem == 0) || (C.n_elem == 0) )
    {
-          Mat<eT> out_slice(              out.slice_memptr(i),  M.n_rows, C.n_cols, false, true);
-    const Mat<eT>   C_slice(const_cast<eT*>(C.slice_memptr(i)), C.n_rows, C.n_cols, false, true);
-    
-    out_slice = M * C_slice;
+    out.zeros();
+    }
+  else
+    {
+    for(uword i=0; i < C.n_slices; ++i)
+      {
+            Mat<eT> out_slice(              out.slice_memptr(i),  M.n_rows, C.n_cols, false, true);
+      const Mat<eT>   C_slice(const_cast<eT*>(C.slice_memptr(i)), C.n_rows, C.n_cols, false, true);
+      
+      out_slice = M * C_slice;
+      }
    }
  
  return out;
@@ -795,6 +857,8 @@ subview_cube_each2_aux::operator_plus
    
    arma_conform_check_bounds( (slice >= p_n_slices), "each_slice(): index out of bounds" );
    
+    if(p_n_elem_slice == 0)  { continue; }
+    
    arrayops::inplace_plus(out.slice_memptr(slice), A_mem, p_n_elem_slice);
    }
  
@@ -840,6 +904,8 @@ subview_cube_each2_aux::operator_minus
    
    arma_conform_check_bounds( (slice >= p_n_slices), "each_slice(): index out of bounds" );
    
+    if(p_n_elem_slice == 0)  { continue; }
+    
    arrayops::inplace_minus(out.slice_memptr(slice), A_mem, p_n_elem_slice);
    }
  
@@ -884,6 +950,8 @@ subview_cube_each2_aux::operator_minus
    
    arma_conform_check_bounds( (slice >= p_n_slices), "each_slice(): index out of bounds" );
    
+    if( (p_n_rows == 0) || (p_n_cols == 0) )  { continue; }
+    
          Mat<eT> out_slice(              out.slice_memptr(slice),  p_n_rows, p_n_cols, false, true);
    const Mat<eT>   p_slice(const_cast<eT*>(p.slice_memptr(slice)), p_n_rows, p_n_cols, false, true);
    
@@ -932,6 +1000,8 @@ subview_cube_each2_aux::operator_schur
    
    arma_conform_check_bounds( (slice >= p_n_slices), "each_slice(): index out of bounds" );
    
+    if(p_n_elem_slice == 0)  { continue; }
+    
    arrayops::inplace_mul(out.slice_memptr(slice), A_mem, p_n_elem_slice);
    }
  
@@ -977,6 +1047,8 @@ subview_cube_each2_aux::operator_div
    
    arma_conform_check_bounds( (slice >= p_n_slices), "each_slice(): index out of bounds" );
    
+    if(p_n_elem_slice == 0)  { continue; }
+    
    arrayops::inplace_div(out.slice_memptr(slice), A_mem, p_n_elem_slice);
    }
  
@@ -1021,6 +1093,8 @@ subview_cube_each2_aux::operator_div
    
    arma_conform_check_bounds( (slice >= p_n_slices), "each_slice(): index out of bounds" );
    
+    if( (p_n_rows == 0) || (p_n_cols == 0) )  { continue; }
+    
          Mat<eT> out_slice(              out.slice_memptr(slice),  p_n_rows, p_n_cols, false, true);
    const Mat<eT>   p_slice(const_cast<eT*>(p.slice_memptr(slice)), p_n_rows, p_n_cols, false, true);
    
@@ -117,6 +117,8 @@ subview_cube<eT>::inplace_op(const eT val)
  const uword t_n_cols   = t.n_cols;
  const uword t_n_slices = t.n_slices;
  
+  if( (t_n_rows == 0) || (t_n_cols == 0) )  { return; }
+  
  for(uword s=0; s < t_n_slices; ++s)
  for(uword c=0; c < t_n_cols;   ++c)
    {
@@ -150,6 +152,8 @@ subview_cube<eT>::inplace_op(const BaseCube<eT,T1>& in, const char* identifier)
  
  arma_conform_assert_same_size(t, P, identifier);
  
+  if( (t_n_rows == 0) || (t_n_cols == 0) || (t_n_slices == 0) )  { return; }
+  
  const bool use_mp      = arma_config::openmp && ProxyCube<T1>::use_mp && mp_gate<eT>::eval(t.n_elem);
  const bool has_overlap = P.has_overlap(t);
  
@@ -258,6 +262,8 @@ subview_cube<eT>::inplace_op(const subview_cube<eT>& x, const char* identifier)
  const uword t_n_cols   = t.n_cols;
  const uword t_n_slices = t.n_slices;
  
+  if( (t_n_rows == 0) || (t_n_cols == 0) )  { return; }
+  
  for(uword s=0; s < t_n_slices; ++s)
  for(uword c=0; c < t_n_cols;   ++c)
    {
@@ -1174,6 +1180,8 @@ subview_cube<eT>::replace(const eT old_val, const eT new_val)
  const uword local_n_cols   = n_cols;
  const uword local_n_slices = n_slices;
  
+  if( (local_n_rows == 0) || (local_n_cols == 0) )  { return; }
+  
  for(uword slice = 0; slice < local_n_slices; ++slice)
    {
    for(uword col = 0; col < local_n_cols; ++col)
@@ -1196,6 +1204,8 @@ subview_cube<eT>::clean(const typename get_pod_type<eT>::result threshold)
  const uword local_n_cols   = n_cols;
  const uword local_n_slices = n_slices;
  
+  if( (local_n_rows == 0) || (local_n_cols == 0) )  { return; }
+  
  for(uword slice = 0; slice < local_n_slices; ++slice)
    {
    for(uword col = 0; col < local_n_cols; ++col)
@@ -1216,18 +1226,20 @@ subview_cube<eT>::clamp(const eT min_val, const eT max_val)
  
  if(is_cx<eT>::no)
    {
-    arma_conform_check( (access::tmp_real(min_val) > access::tmp_real(max_val)), "subview_cube::clamp(): min_val must be less than max_val" );
+    arma_conform_check( ((access::tmp_real(min_val) <= access::tmp_real(max_val)) == false), "subview_cube::clamp(): min_val must be less than max_val" );
    }
  else
    {
-    arma_conform_check( (access::tmp_real(min_val) > access::tmp_real(max_val)), "subview_cube::clamp(): real(min_val) must be less than real(max_val)" );
-    arma_conform_check( (access::tmp_imag(min_val) > access::tmp_imag(max_val)), "subview_cube::clamp(): imag(min_val) must be less than imag(max_val)" );
+    arma_conform_check( ((access::tmp_real(min_val) <= access::tmp_real(max_val)) == false), "subview_cube::clamp(): real(min_val) must be less than real(max_val)" );
+    arma_conform_check( ((access::tmp_imag(min_val) <= access::tmp_imag(max_val)) == false), "subview_cube::clamp(): imag(min_val) must be less than imag(max_val)" );
    }
  
  const uword local_n_rows   = n_rows;
  const uword local_n_cols   = n_cols;
  const uword local_n_slices = n_slices;
  
+  if( (local_n_rows == 0) || (local_n_cols == 0) )  { return; }
+  
  for(uword slice = 0; slice < local_n_slices; ++slice)
    {
    for(uword col = 0; col < local_n_cols; ++col)
@@ -1250,6 +1262,8 @@ subview_cube<eT>::fill(const eT val)
  const uword local_n_cols   = n_cols;
  const uword local_n_slices = n_slices;
  
+  if( (local_n_rows == 0) || (local_n_cols == 0) )  { return; }
+  
  for(uword slice = 0; slice < local_n_slices; ++slice)
    {
    for(uword col = 0; col < local_n_cols; ++col)
@@ -1272,6 +1286,8 @@ subview_cube<eT>::zeros()
  const uword local_n_cols   = n_cols;
  const uword local_n_slices = n_slices;
  
+  if( (local_n_rows == 0) || (local_n_cols == 0) )  { return; }
+  
  for(uword slice = 0; slice < local_n_slices; ++slice)
    {
    for(uword col = 0; col < local_n_cols; ++col)
@@ -1306,6 +1322,8 @@ subview_cube<eT>::randu()
  const uword local_n_cols   = n_cols;
  const uword local_n_slices = n_slices;
  
+  if( (local_n_rows == 0) || (local_n_cols == 0) )  { return; }
+  
  for(uword slice = 0; slice < local_n_slices; ++slice)
    {
    for(uword col = 0; col < local_n_cols; ++col)
@@ -1328,6 +1346,8 @@ subview_cube<eT>::randn()
  const uword local_n_cols   = n_cols;
  const uword local_n_slices = n_slices;
  
+  if( (local_n_rows == 0) || (local_n_cols == 0) )  { return; }
+  
  for(uword slice = 0; slice < local_n_slices; ++slice)
    {
    for(uword col = 0; col < local_n_cols; ++col)
@@ -1352,11 +1372,14 @@ subview_cube<eT>::is_finite() const
  const uword local_n_cols   = n_cols;
  const uword local_n_slices = n_slices;
  
-  for(uword slice = 0; slice < local_n_slices; ++slice)
+  if( (local_n_rows != 0) && (local_n_cols != 0) )
    {
-    for(uword col = 0; col < local_n_cols; ++col)
+    for(uword slice = 0; slice < local_n_slices; ++slice)
      {
-      if(arrayops::is_finite(slice_colptr(slice,col), local_n_rows) == false)  { return false; }
+      for(uword col = 0; col < local_n_cols; ++col)
+        {
+        if(arrayops::is_finite(slice_colptr(slice,col), local_n_rows) == false)  { return false; }
+        }
      }
    }
  
@@ -1372,10 +1395,16 @@ subview_cube<eT>::is_zero(const typename get_pod_type<eT>::result tol) const
  {
  arma_debug_sigprint();
  
+  typedef typename get_pod_type<elem_type>::result T;
+  
+  arma_conform_check( ((tol >= T(0)) == false), "is_zero(): parameter 'tol' must be >= 0" );
+  
  const uword local_n_rows   = n_rows;
  const uword local_n_cols   = n_cols;
  const uword local_n_slices = n_slices;
  
+  if( (local_n_rows == 0) || (local_n_cols == 0) || (local_n_slices == 0) )  { return false; }
+  
  for(uword slice = 0; slice < local_n_slices; ++slice)
    {
    for(uword col = 0; col < local_n_cols; ++col)
@@ -1402,11 +1431,14 @@ subview_cube<eT>::has_inf() const
  const uword local_n_cols   = n_cols;
  const uword local_n_slices = n_slices;
  
-  for(uword slice = 0; slice < local_n_slices; ++slice)
+  if( (local_n_rows != 0) && (local_n_cols != 0) )
    {
-    for(uword col = 0; col < local_n_cols; ++col)
+    for(uword slice = 0; slice < local_n_slices; ++slice)
      {
-      if(arrayops::has_inf(slice_colptr(slice,col), local_n_rows))  { return true; }
+      for(uword col = 0; col < local_n_cols; ++col)
+        {
+        if(arrayops::has_inf(slice_colptr(slice,col), local_n_rows))  { return true; }
+        }
      }
    }
  
@@ -1428,11 +1460,14 @@ subview_cube<eT>::has_nan() const
  const uword local_n_cols   = n_cols;
  const uword local_n_slices = n_slices;
  
-  for(uword slice = 0; slice < local_n_slices; ++slice)
+  if( (local_n_rows != 0) && (local_n_cols != 0) )
    {
-    for(uword col = 0; col < local_n_cols; ++col)
+    for(uword slice = 0; slice < local_n_slices; ++slice)
      {
-      if(arrayops::has_nan(slice_colptr(slice,col), local_n_rows))  { return true; }
+      for(uword col = 0; col < local_n_cols; ++col)
+        {
+        if(arrayops::has_nan(slice_colptr(slice,col), local_n_rows))  { return true; }
+        }
      }
    }
  
@@ -1454,11 +1489,14 @@ subview_cube<eT>::has_nonfinite() const
  const uword local_n_cols   = n_cols;
  const uword local_n_slices = n_slices;
  
-  for(uword slice = 0; slice < local_n_slices; ++slice)
+  if( (local_n_rows != 0) && (local_n_cols != 0) )
    {
-    for(uword col = 0; col < local_n_cols; ++col)
+    for(uword slice = 0; slice < local_n_slices; ++slice)
      {
-      if(arrayops::is_finite(slice_colptr(slice,col), local_n_rows) == false)  { return true; }
+      for(uword col = 0; col < local_n_cols; ++col)
+        {
+        if(arrayops::is_finite(slice_colptr(slice,col), local_n_rows) == false)  { return true; }
+        }
      }
    }
  
@@ -1614,7 +1652,7 @@ arma_inline
 eT*
 subview_cube<eT>::slice_colptr(const uword in_slice, const uword in_col)
  {
-  return & access::rw((const_cast< Cube<eT>& >(m)).mem[  (in_slice + aux_slice1)*m.n_elem_slice + (in_col + aux_col1)*m.n_rows + aux_row1  ]);
+  return access::rwp( m.mem + ( (in_slice + aux_slice1)*m.n_elem_slice + (in_col + aux_col1)*m.n_rows + aux_row1 ) );
  }


@@ -1624,7 +1662,7 @@ arma_inline
 const eT*
 subview_cube<eT>::slice_colptr(const uword in_slice, const uword in_col) const
  {
-  return & m.mem[ (in_slice + aux_slice1)*m.n_elem_slice + (in_col + aux_col1)*m.n_rows + aux_row1 ];
+  return m.mem + ( (in_slice + aux_slice1)*m.n_elem_slice + (in_col + aux_col1)*m.n_rows + aux_row1 );
  }


@@ -1704,7 +1742,7 @@ void
 subview_cube<eT>::extract(Cube<eT>& out, const subview_cube<eT>& in)
  {
  arma_debug_sigprint();
-
+  
  // NOTE: we're assuming that the cube has already been set to the correct size and there is no aliasing;
  // size setting and alias checking is done by either the Cube constructor or operator=()
  
@@ -1714,6 +1752,8 @@ subview_cube<eT>::extract(Cube<eT>& out, const subview_cube<eT>& in)
  
  arma_debug_print(arma_str::format("out.n_rows: %u; out.n_cols: %u; out.n_slices: %u; in.m.n_rows: %u; in.m.n_cols: %u; in.m.n_slices: %u") % out.n_rows % out.n_cols % out.n_slices % in.m.n_rows % in.m.n_cols % in.m.n_slices);
  
+  if( (n_rows == 0) || (n_cols == 0) )  { return; }
+  
  if( (in.aux_row1 == 0) && (n_rows == in.m.n_rows) )
    {
    for(uword s=0; s < n_slices; ++s)
@@ -1747,6 +1787,8 @@ subview_cube<eT>::plus_inplace(Cube<eT>& out, const subview_cube<eT>& in)
  const uword n_cols   = out.n_cols;
  const uword n_slices = out.n_slices;
  
+  if( (n_rows == 0) || (n_cols == 0) )  { return; }
+  
  for(uword slice = 0; slice<n_slices; ++slice)
    {
    for(uword col = 0; col<n_cols; ++col)
@@ -1772,6 +1814,8 @@ subview_cube<eT>::minus_inplace(Cube<eT>& out, const subview_cube<eT>& in)
  const uword n_cols   = out.n_cols;
  const uword n_slices = out.n_slices;
  
+  if( (n_rows == 0) || (n_cols == 0) )  { return; }
+  
  for(uword slice = 0; slice<n_slices; ++slice)
    {
    for(uword col = 0; col<n_cols; ++col)
@@ -1797,6 +1841,8 @@ subview_cube<eT>::schur_inplace(Cube<eT>& out, const subview_cube<eT>& in)
  const uword n_cols   = out.n_cols;
  const uword n_slices = out.n_slices;
  
+  if( (n_rows == 0) || (n_cols == 0) )  { return; }
+  
  for(uword slice = 0; slice<n_slices; ++slice)
    {
    for(uword col = 0; col<n_cols; ++col)
@@ -1822,6 +1868,8 @@ subview_cube<eT>::div_inplace(Cube<eT>& out, const subview_cube<eT>& in)
  const uword n_cols   = out.n_cols;
  const uword n_slices = out.n_slices;
  
+  if( (n_rows == 0) || (n_cols == 0) )  { return; }
+  
  for(uword slice = 0; slice<n_slices; ++slice)
    {
    for(uword col = 0; col<n_cols; ++col)
@@ -157,6 +157,8 @@ subview_each1<parent,mode>::operator= (const Base<eT,T1>& in)
  const uword p_n_rows = p.n_rows;
  const uword p_n_cols = p.n_cols;
  
+  if(p_n_rows == 0)  { return; }
+  
  if(mode == 0) // each column
    {
    for(uword i=0; i < p_n_cols; ++i)
@@ -194,6 +196,8 @@ subview_each1<parent,mode>::operator+= (const Base<eT,T1>& in)
  const uword p_n_rows = p.n_rows;
  const uword p_n_cols = p.n_cols;
  
+  if(p_n_rows == 0)  { return; }
+  
  if(mode == 0) // each column
    {
    for(uword i=0; i < p_n_cols; ++i)
@@ -231,6 +235,8 @@ subview_each1<parent,mode>::operator-= (const Base<eT,T1>& in)
  const uword p_n_rows = p.n_rows;
  const uword p_n_cols = p.n_cols;
  
+  if(p_n_rows == 0)  { return; }
+  
  if(mode == 0) // each column
    {
    for(uword i=0; i < p_n_cols; ++i)
@@ -268,6 +274,8 @@ subview_each1<parent,mode>::operator%= (const Base<eT,T1>& in)
  const uword p_n_rows = p.n_rows;
  const uword p_n_cols = p.n_cols;
  
+  if(p_n_rows == 0)  { return; }
+  
  if(mode == 0) // each column
    {
    for(uword i=0; i < p_n_cols; ++i)
@@ -305,6 +313,8 @@ subview_each1<parent,mode>::operator/= (const Base<eT,T1>& in)
  const uword p_n_rows = p.n_rows;
  const uword p_n_cols = p.n_cols;
  
+  if(p_n_rows == 0)  { return; }
+  
  if(mode == 0) // each column
    {
    for(uword i=0; i < p_n_cols; ++i)
@@ -400,6 +410,8 @@ subview_each2<parent,mode,TB>::operator= (const Base<eT,T1>& in)
      
      arma_conform_check_bounds( (col >= p_n_cols), "each_col(): index out of bounds" );
      
+      if(p_n_rows == 0)  { continue; }
+      
      arrayops::copy( p.colptr(col), A_mem, p_n_rows );
      }
    }
@@ -456,6 +468,8 @@ subview_each2<parent,mode,TB>::operator+= (const Base<eT,T1>& in)
      
      arma_conform_check_bounds( (col >= p_n_cols), "each_col(): index out of bounds" );
      
+      if(p_n_rows == 0)  { continue; }
+      
      arrayops::inplace_plus( p.colptr(col), A_mem, p_n_rows );
      }
    }
@@ -509,6 +523,8 @@ subview_each2<parent,mode,TB>::operator-= (const Base<eT,T1>& in)
      
      arma_conform_check_bounds( (col >= p_n_cols), "each_col(): index out of bounds" );
      
+      if(p_n_rows == 0)  { continue; }
+      
      arrayops::inplace_minus( p.colptr(col), A_mem, p_n_rows );
      }
    }
@@ -562,6 +578,8 @@ subview_each2<parent,mode,TB>::operator%= (const Base<eT,T1>& in)
      
      arma_conform_check_bounds( (col >= p_n_cols), "each_col(): index out of bounds" );
      
+      if(p_n_rows == 0)  { continue; }
+      
      arrayops::inplace_mul( p.colptr(col), A_mem, p_n_rows );
      }
    }
@@ -615,6 +633,8 @@ subview_each2<parent,mode,TB>::operator/= (const Base<eT,T1>& in)
      
      arma_conform_check_bounds( (col >= p_n_cols), "each_col(): index out of bounds" );
      
+      if(p_n_rows == 0)  { continue; }
+      
      arrayops::inplace_div( p.colptr(col), A_mem, p_n_rows );
      }
    }
@@ -666,32 +686,35 @@ subview_each1_aux::operator_plus
  
  const eT* A_mem = A.memptr();
  
-  if(mode == 0) // each column
+  if( (p_n_rows != 0) && (p_n_cols != 0) )
    {
-    for(uword i=0; i < p_n_cols; ++i)
+    if(mode == 0) // each column
      {
-      const eT*   p_mem =   p.colptr(i);
-            eT* out_mem = out.colptr(i);
-      
-      for(uword row=0; row < p_n_rows; ++row)
+      for(uword i=0; i < p_n_cols; ++i)
        {
-        out_mem[row] = p_mem[row] + A_mem[row];
+        const eT*   p_mem =   p.colptr(i);
+              eT* out_mem = out.colptr(i);
+        
+        for(uword row=0; row < p_n_rows; ++row)
+          {
+          out_mem[row] = p_mem[row] + A_mem[row];
+          }
        }
      }
-    }
-  
-  if(mode == 1) // each row
-    {
-    for(uword i=0; i < p_n_cols; ++i)
+    
+    if(mode == 1) // each row
      {
-      const eT*   p_mem =   p.colptr(i);
-            eT* out_mem = out.colptr(i);
-      
-      const eT A_val = A_mem[i];
-      
-      for(uword row=0; row < p_n_rows; ++row)
+      for(uword i=0; i < p_n_cols; ++i)
        {
-        out_mem[row] = p_mem[row] + A_val;
+        const eT*   p_mem =   p.colptr(i);
+              eT* out_mem = out.colptr(i);
+        
+        const eT A_val = A_mem[i];
+        
+        for(uword row=0; row < p_n_rows; ++row)
+          {
+          out_mem[row] = p_mem[row] + A_val;
+          }
        }
      }
    }
@@ -728,32 +751,35 @@ subview_each1_aux::operator_minus
  
  const eT* A_mem = A.memptr();
  
-  if(mode == 0) // each column
+  if( (p_n_rows != 0) && (p_n_cols != 0) )
    {
-    for(uword i=0; i < p_n_cols; ++i)
+    if(mode == 0) // each column
      {
-      const eT*   p_mem =   p.colptr(i);
-            eT* out_mem = out.colptr(i);
-      
-      for(uword row=0; row < p_n_rows; ++row)
+      for(uword i=0; i < p_n_cols; ++i)
        {
-        out_mem[row] = p_mem[row] - A_mem[row];
+        const eT*   p_mem =   p.colptr(i);
+              eT* out_mem = out.colptr(i);
+        
+        for(uword row=0; row < p_n_rows; ++row)
+          {
+          out_mem[row] = p_mem[row] - A_mem[row];
+          }
        }
      }
-    }
-  
-  if(mode == 1) // each row
-    {
-    for(uword i=0; i < p_n_cols; ++i)
+    
+    if(mode == 1) // each row
      {
-      const eT*   p_mem =   p.colptr(i);
-            eT* out_mem = out.colptr(i);
-      
-      const eT A_val = A_mem[i];
-      
-      for(uword row=0; row < p_n_rows; ++row)
+      for(uword i=0; i < p_n_cols; ++i)
        {
-        out_mem[row] = p_mem[row] - A_val;
+        const eT*   p_mem =   p.colptr(i);
+              eT* out_mem = out.colptr(i);
+        
+        const eT A_val = A_mem[i];
+        
+        for(uword row=0; row < p_n_rows; ++row)
+          {
+          out_mem[row] = p_mem[row] - A_val;
+          }
        }
      }
    }
@@ -790,32 +816,35 @@ subview_each1_aux::operator_minus
  
  const eT* A_mem = A.memptr();
  
-  if(mode == 0) // each column
+  if( (p_n_rows != 0) && (p_n_cols != 0) )
    {
-    for(uword i=0; i < p_n_cols; ++i)
+    if(mode == 0) // each column
      {
-      const eT*   p_mem =   p.colptr(i);
-            eT* out_mem = out.colptr(i);
-      
-      for(uword row=0; row < p_n_rows; ++row)
+      for(uword i=0; i < p_n_cols; ++i)
        {
-        out_mem[row] = A_mem[row] - p_mem[row];
+        const eT*   p_mem =   p.colptr(i);
+              eT* out_mem = out.colptr(i);
+        
+        for(uword row=0; row < p_n_rows; ++row)
+          {
+          out_mem[row] = A_mem[row] - p_mem[row];
+          }
        }
      }
-    }
-  
-  if(mode == 1) // each row
-    {
-    for(uword i=0; i < p_n_cols; ++i)
+    
+    if(mode == 1) // each row
      {
-      const eT*   p_mem =   p.colptr(i);
-            eT* out_mem = out.colptr(i);
-      
-      const eT A_val = A_mem[i];
-      
-      for(uword row=0; row < p_n_rows; ++row)
+      for(uword i=0; i < p_n_cols; ++i)
        {
-        out_mem[row] = A_val - p_mem[row];
+        const eT*   p_mem =   p.colptr(i);
+              eT* out_mem = out.colptr(i);
+        
+        const eT A_val = A_mem[i];
+        
+        for(uword row=0; row < p_n_rows; ++row)
+          {
+          out_mem[row] = A_val - p_mem[row];
+          }
        }
      }
    }
@@ -852,32 +881,35 @@ subview_each1_aux::operator_schur
  
  const eT* A_mem = A.memptr();
  
-  if(mode == 0) // each column
+  if( (p_n_rows != 0) && (p_n_cols != 0) )
    {
-    for(uword i=0; i < p_n_cols; ++i)
+    if(mode == 0) // each column
      {
-      const eT*   p_mem =   p.colptr(i);
-            eT* out_mem = out.colptr(i);
-      
-      for(uword row=0; row < p_n_rows; ++row)
+      for(uword i=0; i < p_n_cols; ++i)
        {
-        out_mem[row] = p_mem[row] * A_mem[row];
+        const eT*   p_mem =   p.colptr(i);
+              eT* out_mem = out.colptr(i);
+        
+        for(uword row=0; row < p_n_rows; ++row)
+          {
+          out_mem[row] = p_mem[row] * A_mem[row];
+          }
        }
      }
-    }
-  
-  if(mode == 1) // each row
-    {
-    for(uword i=0; i < p_n_cols; ++i)
+    
+    if(mode == 1) // each row
      {
-      const eT*   p_mem =   p.colptr(i);
-            eT* out_mem = out.colptr(i);
-      
-      const eT A_val = A_mem[i];
-      
-      for(uword row=0; row < p_n_rows; ++row)
+      for(uword i=0; i < p_n_cols; ++i)
        {
-        out_mem[row] = p_mem[row] * A_val;
+        const eT*   p_mem =   p.colptr(i);
+              eT* out_mem = out.colptr(i);
+        
+        const eT A_val = A_mem[i];
+        
+        for(uword row=0; row < p_n_rows; ++row)
+          {
+          out_mem[row] = p_mem[row] * A_val;
+          }
        }
      }
    }
@@ -914,32 +946,35 @@ subview_each1_aux::operator_div
  
  const eT* A_mem = A.memptr();
  
-  if(mode == 0) // each column
+  if( (p_n_rows != 0) && (p_n_cols != 0) )
    {
-    for(uword i=0; i < p_n_cols; ++i)
+    if(mode == 0) // each column
      {
-      const eT*   p_mem =   p.colptr(i);
-            eT* out_mem = out.colptr(i);
-      
-      for(uword row=0; row < p_n_rows; ++row)
+      for(uword i=0; i < p_n_cols; ++i)
        {
-        out_mem[row] = p_mem[row] / A_mem[row];
+        const eT*   p_mem =   p.colptr(i);
+              eT* out_mem = out.colptr(i);
+        
+        for(uword row=0; row < p_n_rows; ++row)
+          {
+          out_mem[row] = p_mem[row] / A_mem[row];
+          }
        }
      }
-    }
-  
-  if(mode == 1) // each row
-    {
-    for(uword i=0; i < p_n_cols; ++i)
+    
+    if(mode == 1) // each row
      {
-      const eT*   p_mem =   p.colptr(i);
-            eT* out_mem = out.colptr(i);
-      
-      const eT A_val = A_mem[i];
-      
-      for(uword row=0; row < p_n_rows; ++row)
+      for(uword i=0; i < p_n_cols; ++i)
        {
-        out_mem[row] = p_mem[row] / A_val;
+        const eT*   p_mem =   p.colptr(i);
+              eT* out_mem = out.colptr(i);
+        
+        const eT A_val = A_mem[i];
+        
+        for(uword row=0; row < p_n_rows; ++row)
+          {
+          out_mem[row] = p_mem[row] / A_val;
+          }
        }
      }
    }
@@ -976,32 +1011,35 @@ subview_each1_aux::operator_div
  
  const eT* A_mem = A.memptr();
  
-  if(mode == 0) // each column
+  if( (p_n_rows != 0) && (p_n_cols != 0) )
    {
-    for(uword i=0; i < p_n_cols; ++i)
+    if(mode == 0) // each column
      {
-      const eT*   p_mem =   p.colptr(i);
-            eT* out_mem = out.colptr(i);
-      
-      for(uword row=0; row < p_n_rows; ++row)
+      for(uword i=0; i < p_n_cols; ++i)
        {
-        out_mem[row] = A_mem[row] / p_mem[row];
+        const eT*   p_mem =   p.colptr(i);
+              eT* out_mem = out.colptr(i);
+        
+        for(uword row=0; row < p_n_rows; ++row)
+          {
+          out_mem[row] = A_mem[row] / p_mem[row];
+          }
        }
      }
-    }
-  
-  if(mode == 1) // each row
-    {
-    for(uword i=0; i < p_n_cols; ++i)
+    
+    if(mode == 1) // each row
      {
-      const eT*   p_mem =   p.colptr(i);
-            eT* out_mem = out.colptr(i);
-      
-      const eT A_val = A_mem[i];
-      
-      for(uword row=0; row < p_n_rows; ++row)
+      for(uword i=0; i < p_n_cols; ++i)
        {
-        out_mem[row] = A_val / p_mem[row];
+        const eT*   p_mem =   p.colptr(i);
+              eT* out_mem = out.colptr(i);
+        
+        const eT A_val = A_mem[i];
+        
+        for(uword row=0; row < p_n_rows; ++row)
+          {
+          out_mem[row] = A_val / p_mem[row];
+          }
        }
      }
    }
@@ -1058,6 +1096,8 @@ subview_each2_aux::operator_plus
      
      arma_conform_check_bounds( (col >= p_n_cols), "each_col(): index out of bounds" );
      
+      if(p_n_rows == 0)  { continue; }
+      
      arrayops::inplace_plus( out.colptr(col), A_mem, p_n_rows );
      }
    }
@@ -1120,6 +1160,8 @@ subview_each2_aux::operator_minus
      
      arma_conform_check_bounds( (col >= p_n_cols), "each_col(): index out of bounds" );
      
+      if(p_n_rows == 0)  { continue; }
+      
      arrayops::inplace_minus( out.colptr(col), A_mem, p_n_rows );
      }
    }
@@ -1182,6 +1224,8 @@ subview_each2_aux::operator_minus
      
      arma_conform_check_bounds( (col >= p_n_cols), "each_col(): index out of bounds" );
      
+      if(p_n_rows == 0)  { continue; }
+      
      const eT*   p_mem =   p.colptr(col);
            eT* out_mem = out.colptr(col);
      
@@ -1250,6 +1294,8 @@ subview_each2_aux::operator_schur
      
      arma_conform_check_bounds( (col >= p_n_cols), "each_col(): index out of bounds" );
      
+      if(p_n_rows == 0)  { continue; }
+      
      arrayops::inplace_mul( out.colptr(col), A_mem, p_n_rows );
      }
    }
@@ -1312,6 +1358,8 @@ subview_each2_aux::operator_div
      
      arma_conform_check_bounds( (col >= p_n_cols), "each_col(): index out of bounds" );
      
+      if(p_n_rows == 0)  { continue; }
+      
      arrayops::inplace_div( out.colptr(col), A_mem, p_n_rows );
      }
    }
@@ -1374,6 +1422,8 @@ subview_each2_aux::operator_div
      
      arma_conform_check_bounds( (col >= p_n_cols), "each_col(): index out of bounds" );
      
+      if(p_n_rows == 0)  { continue; }
+      
      const eT*   p_mem =   p.colptr(col);
            eT* out_mem = out.colptr(col);
      
@@ -95,6 +95,8 @@ subview<eT>::inplace_op(const eT val)
  const uword s_n_rows = s.n_rows;
  const uword s_n_cols = s.n_cols;
  
+  if( (s_n_rows == 0) || (s_n_cols == 0) )  { return; }
+  
  if(s_n_rows == 1)
    {
    Mat<eT>& A = const_cast< Mat<eT>& >(s.m);
@@ -151,6 +153,8 @@ subview<eT>::inplace_op(const Base<eT,T1>& in, const char* identifier)
  
  arma_conform_assert_same_size(s, P, identifier);
  
+  if( (s_n_rows == 0) || (s_n_cols == 0) )  { return; }
+  
  const bool use_mp      = arma_config::openmp && Proxy<T1>::use_mp && mp_gate<eT>::eval(s.n_elem);
  const bool has_overlap = P.has_overlap(s);
  
@@ -348,8 +352,10 @@ subview<eT>::inplace_op(const subview<eT>& x, const char* identifier)
  
  arma_conform_assert_same_size(s, x, identifier);
  
-  const uword s_n_cols = s.n_cols;
  const uword s_n_rows = s.n_rows;
+  const uword s_n_cols = s.n_cols;
+  
+  if( (s_n_rows == 0) || (s_n_cols == 0) )  { return; }
  
  if(s_n_rows == 1)
    {
@@ -606,7 +612,8 @@ subview<eT>::operator=(const SpBase<eT, T1>& x)
  // Clear the subview.
  zeros();
  
-  // Iterate through the sparse subview and set the nonzero values appropriately.
+  if(p.get_n_nonzero() == 0)  { return; }
+  
  typename SpProxy<T1>::const_iterator_type cit     = p.begin();
  typename SpProxy<T1>::const_iterator_type cit_end = p.end();
  
@@ -631,7 +638,8 @@ subview<eT>::operator+=(const SpBase<eT, T1>& x)
  
  arma_conform_assert_same_size(n_rows, n_cols, p.get_n_rows(), p.get_n_cols(), "addition");
  
-  // Iterate through the sparse subview and add its values.
+  if(p.get_n_nonzero() == 0)  { return; }
+  
  typename SpProxy<T1>::const_iterator_type cit     = p.begin();
  typename SpProxy<T1>::const_iterator_type cit_end = p.end();
  
@@ -656,7 +664,8 @@ subview<eT>::operator-=(const SpBase<eT, T1>& x)
  
  arma_conform_assert_same_size(n_rows, n_cols, p.get_n_rows(), p.get_n_cols(), "subtraction");
  
-  // Iterate through the sparse subview and subtract its values.
+  if(p.get_n_nonzero() == 0)  { return; }
+  
  typename SpProxy<T1>::const_iterator_type cit     = p.begin();
  typename SpProxy<T1>::const_iterator_type cit_end = p.end();
  
@@ -725,13 +734,12 @@ subview<eT>::operator/=(const SpBase<eT, T1>& x)
  {
  arma_debug_sigprint();
  
+  // NOTE: use of this function is not advised; it is implemented only for completeness
+  
  const SpProxy<T1> p(x.get_ref());
  
  arma_conform_assert_same_size(n_rows, n_cols, p.get_n_rows(), p.get_n_cols(), "element-wise division");
  
-  // This is probably going to fill your subview with a bunch of NaNs,
-  // so I'm not going to bother to implement it fast.
-  // You can have slow NaNs.  They're fine too.
  for(uword c = 0; c < n_cols; ++c)
  for(uword r = 0; r < n_rows; ++r)
    {
@@ -968,35 +976,14 @@ subview<eT>::replace(const eT old_val, const eT new_val)
  
  subview<eT>& s = *this;
  
-  const uword s_n_cols = s.n_cols;
  const uword s_n_rows = s.n_rows;
+  const uword s_n_cols = s.n_cols;
  
-  if(s_n_rows == 1)
+  if(s_n_rows == 0)  { return; }
+  
+  if( (s.aux_row1 == 0) && (s_n_rows == s.m.n_rows) )
    {
-    Mat<eT>& A = const_cast< Mat<eT>& >(s.m);
-    
-    const uword A_n_rows = A.n_rows;
-    
-    eT* Aptr = &(A.at(s.aux_row1,s.aux_col1));
-    
-    if(arma_isnan(old_val))
-      {
-      for(uword ucol=0; ucol < s_n_cols; ++ucol)
-        {
-        (*Aptr) = (arma_isnan(*Aptr)) ? new_val : (*Aptr);
-        
-        Aptr += A_n_rows;
-        }
-      }
-    else
-      {
-      for(uword ucol=0; ucol < s_n_cols; ++ucol)
-        {
-        (*Aptr) = ((*Aptr) == old_val) ? new_val : (*Aptr);
-        
-        Aptr += A_n_rows;
-        }
-      }
+    arrayops::replace(s.colptr(0), s.n_elem, old_val, new_val);
    }
  else
    {
@@ -1018,8 +1005,10 @@ subview<eT>::clean(const typename get_pod_type<eT>::result threshold)
  
  subview<eT>& s = *this;
  
-  const uword s_n_cols = s.n_cols;
  const uword s_n_rows = s.n_rows;
+  const uword s_n_cols = s.n_cols;
+  
+  if(s_n_rows == 0)  { return; }
  
  for(uword ucol=0; ucol < s_n_cols; ++ucol)
    {
@@ -1038,18 +1027,20 @@ subview<eT>::clamp(const eT min_val, const eT max_val)
  
  if(is_cx<eT>::no)
    {
-    arma_conform_check( (access::tmp_real(min_val) > access::tmp_real(max_val)), "subview::clamp(): min_val must be less than max_val" );
+    arma_conform_check( ((access::tmp_real(min_val) <= access::tmp_real(max_val)) == false), "subview::clamp(): min_val must be less than max_val" );
    }
  else
    {
-    arma_conform_check( (access::tmp_real(min_val) > access::tmp_real(max_val)), "subview::clamp(): real(min_val) must be less than real(max_val)" );
-    arma_conform_check( (access::tmp_imag(min_val) > access::tmp_imag(max_val)), "subview::clamp(): imag(min_val) must be less than imag(max_val)" );
+    arma_conform_check( ((access::tmp_real(min_val) <= access::tmp_real(max_val)) == false), "subview::clamp(): real(min_val) must be less than real(max_val)" );
+    arma_conform_check( ((access::tmp_imag(min_val) <= access::tmp_imag(max_val)) == false), "subview::clamp(): imag(min_val) must be less than imag(max_val)" );
    }
  
  subview<eT>& s = *this;
  
-  const uword s_n_cols = s.n_cols;
  const uword s_n_rows = s.n_rows;
+  const uword s_n_cols = s.n_cols;
+  
+  if(s_n_rows == 0)  { return; }
  
  for(uword ucol=0; ucol < s_n_cols; ++ucol)
    {
@@ -1068,34 +1059,20 @@ subview<eT>::fill(const eT val)
  
  subview<eT>& s = *this;
  
-  const uword s_n_cols = s.n_cols;
  const uword s_n_rows = s.n_rows;
+  const uword s_n_cols = s.n_cols;
  
-  if(s_n_rows == 1)
+  if(s_n_rows == 0)  { return; }
+  
+  if( (s.aux_row1 == 0) && (s_n_rows == s.m.n_rows) )
    {
-    Mat<eT>& A = const_cast< Mat<eT>& >(s.m);
-    
-    const uword A_n_rows = A.n_rows;
-    
-    eT* Aptr = &(A.at(s.aux_row1,s.aux_col1));
-    
-    for(uword ii=0; ii < s_n_cols; ++ii)
-      {
-      (*Aptr) = val;  Aptr += A_n_rows;
-      }
+    arrayops::inplace_set( s.colptr(0), val, s.n_elem );
    }
  else
    {
-    if( (s.aux_row1 == 0) && (s_n_rows == s.m.n_rows) )
+    for(uword ucol=0; ucol < s_n_cols; ++ucol)
      {
-      arrayops::inplace_set( s.colptr(0), val, s.n_elem );
-      }
-    else
-      {
-      for(uword ucol=0; ucol < s_n_cols; ++ucol)
-        {
-        arrayops::inplace_set( s.colptr(ucol), val, s_n_rows );
-        }
+      arrayops::inplace_set( s.colptr(ucol), val, s_n_rows );
      }
    }
  }
@@ -1109,7 +1086,24 @@ subview<eT>::zeros()
  {
  arma_debug_sigprint();
  
-  (*this).fill(eT(0));
+  subview<eT>& s = *this;
+  
+  const uword s_n_rows = s.n_rows;
+  const uword s_n_cols = s.n_cols;
+  
+  if(s_n_rows == 0)  { return; }
+  
+  if( (s.aux_row1 == 0) && (s_n_rows == s.m.n_rows) )
+    {
+    arrayops::fill_zeros( s.colptr(0), s.n_elem );
+    }
+  else
+    {
+    for(uword ucol=0; ucol < s_n_cols; ++ucol)
+      {
+      arrayops::fill_zeros( s.colptr(ucol), s_n_rows );
+      }
+    }
  }


@@ -1157,15 +1151,26 @@ subview<eT>::randu()
  const uword s_n_rows = s.n_rows;
  const uword s_n_cols = s.n_cols;
  
+  if( (s_n_rows == 0) || (s_n_cols == 0) )  { return; }
+  
  if(s_n_rows == 1)
    {
+    // NOTE: special handling to ensure that the same sequence is generated as per subview_row::randu()
+    
    podarray<eT> tmp(s_n_cols);
    
    eT* tmp_mem = tmp.memptr();
    
    arma_rng::randu<eT>::fill( tmp_mem, s_n_cols );
    
-    for(uword ii=0; ii < s_n_cols; ++ii)  { at(0,ii) = tmp_mem[ii]; }
+    eT* mem_ptr = startptr();
+    
+    const uword m_n_rows = s.m.n_rows;
+    
+    for(uword ii=0; ii < s_n_cols; ++ii)
+      {
+      (*mem_ptr) = tmp_mem[ii];  mem_ptr += m_n_rows;
+      }
    }
  else
    {
@@ -1197,15 +1202,26 @@ subview<eT>::randn()
  const uword s_n_rows = s.n_rows;
  const uword s_n_cols = s.n_cols;
  
+  if( (s_n_rows == 0) || (s_n_cols == 0) )  { return; }
+  
  if(s_n_rows == 1)
    {
+    // NOTE: special handling to ensure that the same sequence is generated as per subview_row::randu()
+    
    podarray<eT> tmp(s_n_cols);
    
    eT* tmp_mem = tmp.memptr();
    
    arma_rng::randn<eT>::fill( tmp_mem, s_n_cols );
    
-    for(uword ii=0; ii < s_n_cols; ++ii)  { at(0,ii) = tmp_mem[ii]; }
+    eT* mem_ptr = startptr();
+    
+    const uword m_n_rows = s.m.n_rows;
+    
+    for(uword ii=0; ii < s_n_cols; ++ii)
+      {
+      (*mem_ptr) = tmp_mem[ii];  mem_ptr += m_n_rows;
+      }
    }
  else
    {
@@ -1410,7 +1426,7 @@ arma_inline
 eT*
 subview<eT>::colptr(const uword in_col)
  {
-  return & access::rw((const_cast< Mat<eT>& >(m)).mem[ (in_col + aux_col1)*m.n_rows + aux_row1 ]);
+  return access::rwp( m.mem + ((in_col + aux_col1)*m.n_rows + aux_row1) );
  }


@@ -1420,7 +1436,27 @@ arma_inline
 const eT*
 subview<eT>::colptr(const uword in_col) const
  {
-  return & m.mem[ (in_col + aux_col1)*m.n_rows + aux_row1 ];
+  return m.mem + ((in_col + aux_col1)*m.n_rows + aux_row1);
+  }
+
+
+
+template<typename eT>
+arma_inline
+eT*
+subview<eT>::startptr()
+  {
+  return access::rwp( m.mem + (aux_col1*m.n_rows + aux_row1) );
+  }
+
+
+
+template<typename eT>
+arma_inline
+const eT*
+subview<eT>::startptr() const
+  {
+  return m.mem + (aux_col1*m.n_rows + aux_row1);
  }


@@ -1483,9 +1519,12 @@ subview<eT>::is_finite() const
  const uword local_n_rows = n_rows;
  const uword local_n_cols = n_cols;
  
-  for(uword ii=0; ii<local_n_cols; ++ii)
+  if(local_n_rows != 0)
    {
-    if(arrayops::is_finite(colptr(ii), local_n_rows) == false)  { return false; }
+    for(uword ii=0; ii<local_n_cols; ++ii)
+      {
+      if(arrayops::is_finite(colptr(ii), local_n_rows) == false)  { return false; }
+      }
    }
  
  return true;
@@ -1500,10 +1539,16 @@ subview<eT>::is_zero(const typename get_pod_type<eT>::result tol) const
  {
  arma_debug_sigprint();
  
+  typedef typename get_pod_type<eT>::result T;
+  
+  arma_conform_check( ((tol >= T(0)) == false), "is_zero(): parameter 'tol' must be >= 0" );
+  
  const uword local_n_rows = n_rows;
  const uword local_n_cols = n_cols;
  
-  for(uword ii=0; ii<local_n_cols; ++ii)
+  if( (local_n_rows == 0) || (local_n_cols == 0) )  { return false; }
+  
+  for(uword ii=0; ii < local_n_cols; ++ii)
    {
    if(arrayops::is_zero(colptr(ii), local_n_rows, tol) == false)  { return false; }
    }
@@ -1525,9 +1570,12 @@ subview<eT>::has_inf() const
  const uword local_n_rows = n_rows;
  const uword local_n_cols = n_cols;
  
-  for(uword ii=0; ii<local_n_cols; ++ii)
+  if(local_n_rows != 0)
    {
-    if(arrayops::has_inf(colptr(ii), local_n_rows))  { return true; }
+    for(uword ii=0; ii<local_n_cols; ++ii)
+      {
+      if(arrayops::has_inf(colptr(ii), local_n_rows))  { return true; }
+      }
    }
  
  return false;
@@ -1547,9 +1595,12 @@ subview<eT>::has_nan() const
  const uword local_n_rows = n_rows;
  const uword local_n_cols = n_cols;
  
-  for(uword ii=0; ii<local_n_cols; ++ii)
+  if(local_n_rows != 0)
    {
-    if(arrayops::has_nan(colptr(ii), local_n_rows))  { return true; }
+    for(uword ii=0; ii<local_n_cols; ++ii)
+      {
+      if(arrayops::has_nan(colptr(ii), local_n_rows))  { return true; }
+      }
    }
  
  return false;
@@ -1569,9 +1620,12 @@ subview<eT>::has_nonfinite() const
  const uword local_n_rows = n_rows;
  const uword local_n_cols = n_cols;
  
-  for(uword ii=0; ii<local_n_cols; ++ii)
+  if(local_n_rows != 0)
    {
-    if(arrayops::is_finite(colptr(ii), local_n_rows) == false)  { return true; }
+    for(uword ii=0; ii<local_n_cols; ++ii)
+      {
+      if(arrayops::is_finite(colptr(ii), local_n_rows) == false)  { return true; }
+      }
    }
  
  return false;
@@ -1590,64 +1644,66 @@ subview<eT>::extract(Mat<eT>& out, const subview<eT>& in)
  // NOTE: we're assuming that the matrix has already been set to the correct size and there is no aliasing;
  // size setting and alias checking is done by either the Mat constructor or operator=()
  
-  const uword n_rows = in.n_rows;  // number of rows in the subview
-  const uword n_cols = in.n_cols;  // number of columns in the subview
-  
  arma_debug_print(arma_str::format("out.n_rows: %u; out.n_cols: %u; in.m.n_rows: %u; in.m.n_cols: %u") % out.n_rows % out.n_cols % in.m.n_rows % in.m.n_cols );
  
+  const uword n_rows = in.n_rows;
+  const uword n_cols = in.n_cols;
  
-  if(in.is_vec())
+  if( (n_rows == 0) || (n_cols == 0) )  { return; }
+  
+  if(n_cols == 1)
    {
-    if(n_cols == 1)   // a column vector
-      {
-      arma_debug_print("subview::extract(): copying col");
-      
-      // in.colptr(0) is the first column of the subview, taking into account any row offset
-      arrayops::copy( out.memptr(), in.colptr(0), n_rows );
-      }
-    else
-    if(n_rows == 1)   // a row vector
-      {
-      arma_debug_print("subview::extract(): copying row)");
-      
-      eT* out_mem = out.memptr();
-      
-      const uword X_n_rows = in.m.n_rows;
-      
-      const eT* Xptr = &(in.m.at(in.aux_row1,in.aux_col1));
-      
-      uword j;
-      
-      for(j=1; j < n_cols; j+=2)
-        {
-        const eT tmp1 = (*Xptr);  Xptr += X_n_rows;
-        const eT tmp2 = (*Xptr);  Xptr += X_n_rows;
-        
-        (*out_mem) = tmp1;  out_mem++;
-        (*out_mem) = tmp2;  out_mem++;
-        }
-      
-      if((j-1) < n_cols)
-        {
-        (*out_mem) = (*Xptr);
-        }
-      }
-    }
-  else   // general submatrix
-    {
-    arma_debug_print("subview::extract(): general submatrix");
+    arma_debug_print("subview::extract(): copying col");
    
-    if( (in.aux_row1 == 0) && (n_rows == in.m.n_rows) )
+    // in.colptr(0) is the first column of the subview, taking into account any row offset
+    arrayops::copy( out.memptr(), in.colptr(0), n_rows );
+    
+    return;
+    }
+  
+  if(n_rows == 1)
+    {
+    arma_debug_print("subview::extract(): copying row");
+    
+    eT* out_mem = out.memptr();
+    
+    const uword X_n_rows = in.m.n_rows;
+    
+    const eT* Xptr = &(in.m.at(in.aux_row1,in.aux_col1));
+    
+    uword j;
+    
+    for(j=1; j < n_cols; j+=2)
      {
-      arrayops::copy( out.memptr(), in.colptr(0), in.n_elem );
+      const eT tmp1 = (*Xptr);  Xptr += X_n_rows;
+      const eT tmp2 = (*Xptr);  Xptr += X_n_rows;
+      
+      (*out_mem) = tmp1;  out_mem++;
+      (*out_mem) = tmp2;  out_mem++;
      }
-    else
+    
+    if((j-1) < n_cols)
      {
-      for(uword col=0; col < n_cols; ++col)
-        {
-        arrayops::copy( out.colptr(col), in.colptr(col), n_rows );
-        }
+      (*out_mem) = (*Xptr);
      }
+    
+    return;
+    }
+  
+  if( (in.aux_row1 == 0) && (n_rows == in.m.n_rows) )
+    {
+    arma_debug_print("subview::extract(): contiguous submatrix");
+    
+    arrayops::copy( out.memptr(), in.colptr(0), in.n_elem );
+    
+    return;
+    }
+    
+  arma_debug_print("subview::extract(): general submatrix");
+  
+  for(uword col=0; col < n_cols; ++col)
+    {
+    arrayops::copy( out.colptr(col), in.colptr(col), n_rows );
    }
  }

@@ -1666,6 +1722,8 @@ subview<eT>::plus_inplace(Mat<eT>& out, const subview<eT>& in)
  const uword n_rows = in.n_rows;
  const uword n_cols = in.n_cols;
  
+  if( (n_rows == 0) || (n_cols == 0) )  { return; }
+  
  if(n_rows == 1)
    {
    eT* out_mem = out.memptr();
@@ -1714,6 +1772,8 @@ subview<eT>::minus_inplace(Mat<eT>& out, const subview<eT>& in)
  const uword n_rows = in.n_rows;
  const uword n_cols = in.n_cols;
  
+  if( (n_rows == 0) || (n_cols == 0) )  { return; }
+  
  if(n_rows == 1)
    {
    eT* out_mem = out.memptr();
@@ -1762,6 +1822,8 @@ subview<eT>::schur_inplace(Mat<eT>& out, const subview<eT>& in)
  const uword n_rows = in.n_rows;
  const uword n_cols = in.n_cols;
  
+  if( (n_rows == 0) || (n_cols == 0) )  { return; }
+  
  if(n_rows == 1)
    {
    eT* out_mem = out.memptr();
@@ -1810,6 +1872,8 @@ subview<eT>::div_inplace(Mat<eT>& out, const subview<eT>& in)
  const uword n_rows = in.n_rows;
  const uword n_cols = in.n_cols;
  
+  if( (n_rows == 0) || (n_cols == 0) )  { return; }
+  
  if(n_rows == 1)
    {
    eT* out_mem = out.memptr();
@@ -2377,9 +2441,12 @@ subview<eT>::each_col(const std::function< void(Col<eT>&) >& F)
  {
  arma_debug_sigprint();
  
-  for(uword ii=0; ii < n_cols; ++ii)
+  const uword local_n_rows = n_rows;
+  const uword local_n_cols = n_cols;
+  
+  for(uword ii=0; ii < local_n_cols; ++ii)
    {
-    Col<eT> tmp(colptr(ii), n_rows, false, true);
+    Col<eT> tmp(colptr(ii), local_n_rows, false, true);
    F(tmp);
    }
  }
@@ -2393,9 +2460,12 @@ subview<eT>::each_col(const std::function< void(const Col<eT>&) >& F) const
  {
  arma_debug_sigprint();
  
-  for(uword ii=0; ii < n_cols; ++ii)
+  const uword local_n_rows = n_rows;
+  const uword local_n_cols = n_cols;
+  
+  for(uword ii=0; ii < local_n_cols; ++ii)
    {
-    const Col<eT> tmp(colptr(ii), n_rows, false, true);
+    const Col<eT> tmp(colptr(ii), local_n_rows, false, true);
    F(tmp);
    }
  }
@@ -2410,20 +2480,23 @@ subview<eT>::each_row(const std::function< void(Row<eT>&) >& F)
  {
  arma_debug_sigprint();
  
-  podarray<eT> array1(n_cols);
-  podarray<eT> array2(n_cols);
+  const uword local_n_rows = n_rows;
+  const uword local_n_cols = n_cols;
  
-  Row<eT> tmp1( array1.memptr(), n_cols, false, true );
-  Row<eT> tmp2( array2.memptr(), n_cols, false, true );
+  podarray<eT> array1(local_n_cols);
+  podarray<eT> array2(local_n_cols);
+  
+  Row<eT> tmp1( array1.memptr(), local_n_cols, false, true );
+  Row<eT> tmp2( array2.memptr(), local_n_cols, false, true );
  
  eT* tmp1_mem = tmp1.memptr();
  eT* tmp2_mem = tmp2.memptr();
  
  uword ii, jj;
  
-  for(ii=0, jj=1; jj < n_rows; ii+=2, jj+=2)
+  for(ii=0, jj=1; jj < local_n_rows; ii+=2, jj+=2)
    {
-    for(uword col_id = 0; col_id < n_cols; ++col_id)
+    for(uword col_id = 0; col_id < local_n_cols; ++col_id)
      {
      const eT* col_mem = colptr(col_id);
      
@@ -2434,7 +2507,7 @@ subview<eT>::each_row(const std::function< void(Row<eT>&) >& F)
    F(tmp1);
    F(tmp2);
    
-    for(uword col_id = 0; col_id < n_cols; ++col_id)
+    for(uword col_id = 0; col_id < local_n_cols; ++col_id)
      {
      eT* col_mem = colptr(col_id);
      
@@ -2443,7 +2516,7 @@ subview<eT>::each_row(const std::function< void(Row<eT>&) >& F)
      }
    }
  
-  if(ii < n_rows)
+  if(ii < local_n_rows)
    {
    tmp1 = (*this).row(ii);
    
@@ -2462,20 +2535,23 @@ subview<eT>::each_row(const std::function< void(const Row<eT>&) >& F) const
  {
  arma_debug_sigprint();
  
-  podarray<eT> array1(n_cols);
-  podarray<eT> array2(n_cols);
+  const uword local_n_rows = n_rows;
+  const uword local_n_cols = n_cols;
  
-  Row<eT> tmp1( array1.memptr(), n_cols, false, true );
-  Row<eT> tmp2( array2.memptr(), n_cols, false, true );
+  podarray<eT> array1(local_n_cols);
+  podarray<eT> array2(local_n_cols);
+  
+  Row<eT> tmp1( array1.memptr(), local_n_cols, false, true );
+  Row<eT> tmp2( array2.memptr(), local_n_cols, false, true );
  
  eT* tmp1_mem = tmp1.memptr();
  eT* tmp2_mem = tmp2.memptr();
  
  uword ii, jj;
  
-  for(ii=0, jj=1; jj < n_rows; ii+=2, jj+=2)
+  for(ii=0, jj=1; jj < local_n_rows; ii+=2, jj+=2)
    {
-    for(uword col_id = 0; col_id < n_cols; ++col_id)
+    for(uword col_id = 0; col_id < local_n_cols; ++col_id)
      {
      const eT* col_mem = colptr(col_id);
      
@@ -2487,7 +2563,7 @@ subview<eT>::each_row(const std::function< void(const Row<eT>&) >& F) const
    F(tmp2);
    }
  
-  if(ii < n_rows)
+  if(ii < local_n_rows)
    {
    tmp1 = (*this).row(ii);
    
@@ -3264,7 +3340,7 @@ template<typename eT>
 inline
 subview_col<eT>::subview_col(const Mat<eT>& in_m, const uword in_col)
  : subview<eT>(in_m, 0, in_col, in_m.n_rows, 1)
-  , colmem(subview<eT>::colptr(0)) 
+  , colmem(subview<eT>::startptr()) 
  {
  arma_debug_sigprint();
  }
@@ -3275,7 +3351,7 @@ template<typename eT>
 inline
 subview_col<eT>::subview_col(const Mat<eT>& in_m, const uword in_col, const uword in_row1, const uword in_n_rows)
  : subview<eT>(in_m, in_row1, in_col, in_n_rows, 1)
-  , colmem(subview<eT>::colptr(0)) 
+  , colmem(subview<eT>::startptr()) 
  {
  arma_debug_sigprint();
  }
@@ -3455,6 +3531,18 @@ subview_col<eT>::as_row() const



+template<typename eT>
+inline
+void
+subview_col<eT>::replace(const eT old_val, const eT new_val)
+  {
+  arma_debug_sigprint();
+  
+  arrayops::replace( access::rwp(colmem), subview<eT>::n_rows, old_val, new_val );
+  }
+
+
+
 template<typename eT>
 inline
 void
@@ -3491,6 +3579,30 @@ subview_col<eT>::ones()



+template<typename eT>
+inline
+void
+subview_col<eT>::randu()
+  {
+  arma_debug_sigprint();
+  
+  arma_rng::randu<eT>::fill( access::rwp(colmem), subview<eT>::n_rows );
+  }
+
+
+
+template<typename eT>
+inline
+void
+subview_col<eT>::randn()
+  {
+  arma_debug_sigprint();
+  
+  arma_rng::randn<eT>::fill( access::rwp(colmem), subview<eT>::n_rows );
+  }
+
+
+
 template<typename eT>
 inline
 bool
@@ -3505,6 +3617,22 @@ subview_col<eT>::is_finite() const



+template<typename eT>
+inline
+bool
+subview_col<eT>::is_zero(const typename get_pod_type<eT>::result tol) const
+  {
+  arma_debug_sigprint();
+  
+  typedef typename get_pod_type<eT>::result T;
+  
+  arma_conform_check( ((tol >= T(0)) == false), "is_zero(): parameter 'tol' must be >= 0" );
+  
+  return arrayops::is_zero(colmem, subview<eT>::n_rows, tol);
+  }
+
+
+
 template<typename eT>
 inline
 bool
@@ -4268,7 +4396,7 @@ template<typename eT>
 inline
 subview_row<eT>::subview_row(const Mat<eT>& in_m, const uword in_row)
  : subview<eT>(in_m, in_row, 0, 1, in_m.n_cols)
-  , rowmem(subview<eT>::colptr(0))
+  , rowmem(subview<eT>::startptr())
  {
  arma_debug_sigprint();
  }
@@ -4279,7 +4407,7 @@ template<typename eT>
 inline
 subview_row<eT>::subview_row(const Mat<eT>& in_m, const uword in_row, const uword in_col1, const uword in_n_cols)
  : subview<eT>(in_m, in_row, in_col1, 1, in_n_cols)
-  , rowmem(subview<eT>::colptr(0))
+  , rowmem(subview<eT>::startptr())
  {
  arma_debug_sigprint();
  }
@@ -4486,6 +4614,40 @@ subview_row<eT>::as_col() const



+template<typename eT>
+inline
+void
+subview_row<eT>::replace(const eT old_val, const eT new_val)
+  {
+  arma_debug_sigprint();
+  
+  eT* mem_ptr = access::rwp(rowmem);
+  
+  const uword local_s_n_cols = subview<eT>::n_cols;
+  const uword local_m_n_rows = subview<eT>::m.n_rows;
+  
+  if(arma_isnan(old_val))
+    {
+    for(uword ii=0; ii < local_s_n_cols; ++ii)
+      {
+      eT& val = (*mem_ptr);  mem_ptr += local_m_n_rows;
+      
+      val = (arma_isnan(val)) ? new_val : val;
+      }
+    }
+  else
+    {
+    for(uword ii=0; ii < local_s_n_cols; ++ii)
+      {
+      eT& val = (*mem_ptr);  mem_ptr += local_m_n_rows;
+      
+      val = (val == old_val) ? new_val : val;
+      }
+    }
+  }
+
+
+
 template<typename eT>
 inline
 void
@@ -4530,6 +4692,58 @@ subview_row<eT>::ones()



+template<typename eT>
+inline
+void
+subview_row<eT>::randu()
+  {
+  arma_debug_sigprint();
+  
+  const uword local_s_n_cols = subview<eT>::n_cols;
+  const uword local_m_n_rows = subview<eT>::m.n_rows;
+  
+  podarray<eT> tmp(local_s_n_cols);
+  
+  eT* tmp_mem = tmp.memptr();
+  
+  arma_rng::randu<eT>::fill( tmp_mem, local_s_n_cols );
+  
+  eT* mem_ptr = access::rwp(rowmem);
+  
+  for(uword ii=0; ii < local_s_n_cols; ++ii)
+    {
+    (*mem_ptr) = tmp_mem[ii];  mem_ptr += local_m_n_rows;
+    }
+  }
+
+
+
+template<typename eT>
+inline
+void
+subview_row<eT>::randn()
+  {
+  arma_debug_sigprint();
+  
+  const uword local_s_n_cols = subview<eT>::n_cols;
+  const uword local_m_n_rows = subview<eT>::m.n_rows;
+  
+  podarray<eT> tmp(local_s_n_cols);
+  
+  eT* tmp_mem = tmp.memptr();
+  
+  arma_rng::randn<eT>::fill( tmp_mem, local_s_n_cols );
+  
+  eT* mem_ptr = access::rwp(rowmem);
+  
+  for(uword ii=0; ii < local_s_n_cols; ++ii)
+    {
+    (*mem_ptr) = tmp_mem[ii];  mem_ptr += local_m_n_rows;
+    }
+  }
+
+
+
 template<typename eT>
 inline
 bool
@@ -4556,6 +4770,80 @@ subview_row<eT>::is_finite() const



+template<typename eT>
+inline
+bool
+subview_row<eT>::is_zero(const typename get_pod_type<eT>::result tol) const
+  {
+  arma_debug_sigprint();
+  
+  typedef typename get_pod_type<eT>::result T;
+  
+  arma_conform_check( ((tol >= T(0)) == false), "is_zero(): parameter 'tol' must be >= 0" );
+  
+  const uword local_s_n_cols = subview<eT>::n_cols;
+  const uword local_m_n_rows = subview<eT>::m.n_rows;
+  
+  if(local_s_n_cols == 0)  { return false; }
+  
+  const eT* mem_ptr = rowmem;
+  
+  if(is_cx<eT>::yes)
+    {
+    if(tol == T(0))
+      {
+      for(uword ii=0; ii < local_s_n_cols; ++ii)
+        {
+        const eT& val = (*mem_ptr);  mem_ptr += local_m_n_rows;
+        
+        const T val_real = access::tmp_real(val);
+        const T val_imag = access::tmp_imag(val);
+        
+        if(eop_aux::arma_abs(val_real) != T(0))  { return false; }
+        if(eop_aux::arma_abs(val_imag) != T(0))  { return false; }
+        }
+      }
+    else
+      {
+      for(uword ii=0; ii < local_s_n_cols; ++ii)
+        {
+        const eT& val = (*mem_ptr);  mem_ptr += local_m_n_rows;
+        
+        const T val_real = access::tmp_real(val);
+        const T val_imag = access::tmp_imag(val);
+        
+        if( (eop_aux::arma_abs(val_real) <= tol) == false )  { return false; }
+        if( (eop_aux::arma_abs(val_imag) <= tol) == false )  { return false; }
+        }
+      }
+    }
+  else  // not complex
+    {
+    if(tol == T(0))
+      {
+      for(uword ii=0; ii < local_s_n_cols; ++ii)
+        {
+        const eT val = (*mem_ptr);  mem_ptr += local_m_n_rows;
+        
+        if(val != eT(0))  { return false; }
+        }
+      }
+    else
+      {
+      for(uword ii=0; ii < local_s_n_cols; ++ii)
+        {
+        const eT val = (*mem_ptr);  mem_ptr += local_m_n_rows;
+        
+        if( (eop_aux::arma_abs(val) <= tol) == false )  { return false; }
+        }
+      }
+    }
+  
+  return true;
+  }
+
+
+
 template<typename eT>
 inline
 bool
@@ -26,7 +26,7 @@
 #else
  #if   UCHAR_MAX >= 0xff
    typedef unsigned char    u8;
-    typedef          char    s8;
+    typedef          char    s8;  // kept for compatibility with earlier versions of Armadillo
  #elif defined(UINT8_MAX)
    typedef          uint8_t u8;
    typedef           int8_t s8;
Author	SHA1	Message	Date
conrad	36b0cd37ec	patch bump	2026-04-20 00:15:11 +10:00
conrad	59fbefc095	simplifications	2026-04-19 22:59:46 +10:00
conrad	b1f3a185bf	distinguish between default and user supplied tolerance	2026-04-18 23:48:32 +10:00
conrad	adcbf1380a	ensure intermediate results are not NaN	2026-04-18 17:45:48 +10:00
conrad	733533f089	ensure intermediate results are not NaN	2026-04-18 17:09:20 +10:00
conrad	ae6f216a82	ensure suppled tolerances are not NaN	2026-04-18 17:08:51 +10:00
conrad	417bb37042	ensure default tolerances are not NaN	2026-04-18 16:45:02 +10:00
conrad	95cad27904	ensure default tolerance is finite	2026-04-18 14:13:49 +10:00
conrad	3e66e7b1f0	cleanup	2026-04-16 21:39:49 +10:00
conrad	4a6cc3e9a8	patch bump	2026-04-16 15:14:57 +10:00
conrad	0260b7f1dc	fix warning message	2026-04-16 15:09:11 +10:00
conrad	6b180e1943	cleanup	2026-04-16 15:07:09 +10:00
conrad	afec1a5f5a	use the Proxy only when necessary	2026-04-15 14:10:24 +10:00
conrad	7ab5657470	faster handling of compound vector expressions	2026-04-15 13:42:44 +10:00
conrad	fa63e6d717	distinguish between default and user supplied tolerance	2026-04-07 11:33:04 +10:00
conrad	bf69c85cb8	show rcond earlier to avoid potential confusion	2026-04-07 10:56:08 +10:00
conrad	5e888a2fc7	simplifications	2026-04-06 21:14:45 +10:00
conrad	f0db911a5c	handle NaNs when checking ranges	2026-04-06 20:36:34 +10:00
conrad	efff7a8f3f	simplify warning messages	2026-04-06 19:48:48 +10:00
conrad	7f5569ffba	handle NaNs when checking ranges	2026-04-06 19:35:29 +10:00
conrad	7c9ef72802	handle NaNs when checking tolerances	2026-04-05 23:06:49 +10:00
conrad	c75af66d72	ensure consistency with subview_row::randu() and subview_row::randn()	2026-04-05 19:40:55 +10:00
conrad	ce769c625f	handle NaNs when checking tolerances	2026-04-05 02:30:59 +10:00
conrad	f1e65e55de	handle NaNs when checking conformance	2026-04-05 02:22:30 +10:00
conrad	7e4a956dbd	specialisations for randu() and randn()	2026-04-04 19:47:20 +10:00
conrad	43b071020a	handle NaNs when checking tolerances	2026-04-02 13:49:58 +10:00
conrad	f548057ee7	simplifications	2026-04-02 13:44:30 +10:00
conrad	e260407a3e	handle NaNs when checking tolerances	2026-04-02 13:09:39 +10:00
conrad	f049b04688	simplification: implicit handling of NaNs	2026-04-02 12:33:44 +10:00
conrad	8af4d74bd4	rearrange for consistency with other code	2026-04-01 16:33:36 +10:00
conrad	a039d60a47	simplification	2026-03-31 12:42:59 +10:00
conrad	a4634e8888	use correct element type	2026-03-31 12:36:05 +10:00
conrad	df1eec4fb9	add note on how to enable support for std::int8_t and std::uint8_t	2026-03-30 00:26:09 +10:00
conrad	4524c7580f	rearrange ::is_zero() to follow same pattern as arrayops::is_zero()	2026-03-30 00:24:49 +10:00
conrad	536a642b64	add compatibility note	2026-03-28 16:23:34 +10:00
conrad	80e1faa764	shorten temporary suffix and increase its randomness	2026-03-27 11:25:59 +10:00
conrad	4e8e1564e0	simplifications	2026-03-24 12:36:32 +10:00
conrad	cd0a21d242	specialisations for .replace()	2026-03-24 12:27:35 +10:00
conrad	e43f4f7ef9	fix corner case in is_zero(): explicitly handle nan	2026-03-23 15:23:14 +10:00
conrad	f2691c6beb	fix corner case in is_zero(): explicitly handle nan	2026-03-23 15:12:22 +10:00
conrad	825dbf7e60	fix corner case in is_zero(): explicitly handle nan	2026-03-23 12:42:46 +10:00
conrad	ed078509da	fixes for corner cases	2026-03-23 12:17:44 +10:00
conrad	759a36d0b3	fix + specialisations for .is_zero()	2026-03-23 11:59:52 +10:00
conrad	e0d2196ae5	faster scalar operations on diagview	2026-03-21 20:06:48 +10:00
conrad	998c7814bc	use proper function names in error messages	2026-03-21 11:39:52 +10:00
conrad	ebd9209b31	simplify warning messages	2026-03-20 15:34:13 +10:00
conrad	745b02d4d7	simplifications	2026-03-20 14:49:29 +10:00
conrad	b28fd1456c	update list of changes	2026-03-20 12:54:13 +10:00
conrad	44a7a9cfed	add note on arma prefix for span()	2026-03-20 12:38:38 +10:00
conrad	ee9e26902f	increase randomness of temporary filenames	2026-03-19 14:35:44 +10:00
conrad	c14a60deec	update year	2026-03-18 11:50:47 +10:00
conrad	33e382b623	simplifications	2026-03-17 12:07:46 +10:00
conrad	7334664999	patch bump	2026-03-15 18:42:19 +10:00
conrad	f021766215	speedups for blank sparse submatrices	2026-03-15 17:33:41 +10:00
conrad	5491a20833	simplifications	2026-03-13 12:16:51 +10:00
conrad	1cab3be4df	simplifications	2026-03-13 11:52:44 +10:00
conrad	08e1cb5211	specialisation for subview::zeros()	2026-03-13 11:33:39 +10:00
conrad	70c45a2f17	workarounds for ASAN false positives	2026-03-12 18:21:38 +10:00
conrad	2dfed59b94	simplifications	2026-03-12 15:57:37 +10:00
conrad	8bf7834041	simplifications	2026-03-12 15:48:04 +10:00
conrad	1461d33045	simplifications	2026-03-12 15:32:54 +10:00
conrad	e05bc82e7b	speedups for empty subcubes	2026-03-12 15:30:34 +10:00
conrad	9201e8ddd0	speedups for empty cubes	2026-03-12 15:23:18 +10:00
conrad	30dd62780b	speedups for empty cubes	2026-03-12 12:21:15 +10:00
conrad	5dd6c665a5	speedups for empty cubes	2026-03-12 11:55:26 +10:00
conrad	2e6b4ed0a3	speedups for empty cubes	2026-03-11 17:09:31 +10:00
conrad	08c0647e54	speedups for empty matrices	2026-03-11 16:55:26 +10:00
conrad	ff7f5d63e6	speedups for empty matrices	2026-03-11 15:12:59 +10:00
conrad	2288ec1497	remove superfluous comments	2026-03-11 15:12:32 +10:00
conrad	1df5fc83b7	speedups for blank sparse matrices	2026-03-10 15:58:00 +10:00
conrad	81df0a1f93	simplifications	2026-03-10 15:51:02 +10:00
conrad	bceaf09865	speedups for blank sparse submatrices	2026-03-10 13:14:08 +10:00
conrad	3992546579	speedups for blank sparse submatrices	2026-03-10 12:31:16 +10:00
conrad	602f6217e0	speedups for blank sparse submatrices	2026-03-10 12:01:54 +10:00
conrad	449e6f682f	speedups for blank sparse matrices	2026-03-10 11:51:20 +10:00
conrad	03df540096	fix error message	2026-03-09 13:29:19 +10:00
conrad	b21700fc85	check if sizes are the same	2026-03-09 13:25:32 +10:00
conrad	02438fff53	speedups for blank sparse submatrices	2026-03-09 13:17:36 +10:00
conrad	451d5d2cec	speedups for empty submatrices	2026-03-05 15:50:01 +10:00
conrad	534f135ef5	speedups for empty submatrices	2026-03-04 15:32:54 +10:00
conrad	8bd0d6692a	speedups for empty subcubes	2026-03-04 15:24:34 +10:00
conrad	ad1bed2686	speedups for empty submatrices	2026-02-28 14:11:47 +10:00
conrad	36e3d67a28	speedups for empty submatrices	2026-02-27 13:35:17 +10:00
conrad	e3db651df7	speedup for empty submatrices	2026-02-27 13:07:40 +10:00
conrad	fa52e3f5ef	speedup for empty subcubes	2026-02-25 13:11:14 +10:00
conrad	e6b06b21da	speedup for empty matrices	2026-02-23 17:04:55 +10:00
conrad	252708e389	get pointer to first element via dedicated function	2026-02-20 13:17:43 +10:00
conrad	4b468f5009	simplifications	2026-02-20 10:47:28 +10:00
conrad	1244651dda	simpler wording	2026-02-11 17:26:57 +10:00
conrad	e4b96542b3	improve docs for .col_as_mat() and .row_as_mat()	2026-02-10 12:22:25 +10:00
conrad	5701dd07a8	avoid potentially confusing debug message	2026-02-05 15:21:14 +10:00
conrad	bdc89797cd	improved wording	2026-02-03 12:15:10 +10:00
conrad	2110b7d82c	improved wording and layout	2026-02-03 11:53:05 +10:00
conrad	3bcfde3238	avoid repetition	2026-02-02 16:51:23 +10:00
conrad	3495f87581	better wording	2026-02-02 16:49:09 +10:00
conrad	8a24c0d724	expand fill types	2026-02-02 13:33:39 +10:00
conrad	ec75a6107c	expand docs for .fill() with notes on element initialisation during construction	2026-01-30 13:29:45 +10:00
conrad	450e1ba8a5	use explicit initialisation	2026-01-29 13:39:36 +10:00
conrad	a0dcf97054	use explicit initialisation	2026-01-28 17:11:43 +10:00
conrad	cd96c0d9e2	update paper	2026-01-02 12:25:10 +10:00