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armadillo-code/include/armadillo_bits/op_pinv_meat.hpp
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// SPDX-License-Identifier: Apache-2.0
//
// Copyright 2008-2016 Conrad Sanderson (http://conradsanderson.id.au)
// Copyright 2008-2016 National ICT Australia (NICTA)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ------------------------------------------------------------------------
//! \addtogroup op_pinv
//! @{
template<typename T1>
inline
void
op_pinv_default::apply(Mat<typename T1::elem_type>& out, const Op<T1,op_pinv_default>& in)
{
arma_extra_debug_sigprint();
const bool status = op_pinv_default::apply_direct(out, in.m);
if(status == false)
{
out.soft_reset();
arma_stop_runtime_error("pinv(): svd failed");
}
}
template<typename T1>
inline
bool
op_pinv_default::apply_direct(Mat<typename T1::elem_type>& out, const Base<typename T1::elem_type,T1>& expr)
{
arma_extra_debug_sigprint();
typedef typename T1::pod_type T;
constexpr T tol = T(0);
constexpr uword method_id = uword(0);
return op_pinv::apply_direct(out, expr, tol, method_id);
}
//
template<typename T1>
inline
void
op_pinv::apply(Mat<typename T1::elem_type>& out, const Op<T1,op_pinv>& in)
{
arma_extra_debug_sigprint();
typedef typename T1::pod_type T;
const T tol = access::tmp_real(in.aux);
const uword method_id = in.aux_uword_a;
const bool status = op_pinv::apply_direct(out, in.m, tol, method_id);
if(status == false)
{
out.soft_reset();
arma_stop_runtime_error("pinv(): svd failed");
}
}
template<typename T1>
inline
bool
op_pinv::apply_direct(Mat<typename T1::elem_type>& out, const Base<typename T1::elem_type,T1>& expr, typename T1::pod_type tol, const uword method_id)
{
arma_extra_debug_sigprint();
typedef typename T1::elem_type eT;
typedef typename T1::pod_type T;
arma_debug_check((tol < T(0)), "pinv(): tolerance must be >= 0");
// method_id = 0 -> default setting
// method_id = 1 -> use standard algorithm
// method_id = 2 -> use divide and conquer algorithm
Mat<eT> A(expr.get_ref());
if(A.is_empty()) { out.set_size(A.n_cols,A.n_rows); return true; }
if(is_op_diagmat<T1>::value || A.is_diagmat())
{
arma_extra_debug_print("op_pinv: detected diagonal matrix");
return op_pinv::apply_diag(out, A, tol);
}
bool do_sym = false;
const bool is_sym_size_ok = (A.n_rows == A.n_cols) && (A.n_rows > (is_cx<eT>::yes ? uword(20) : uword(40)));
if( (is_sym_size_ok) && (arma_config::optimise_sym) && (auxlib::crippled_lapack(A) == false) )
{
bool is_approx_sym = false;
bool is_approx_sympd = false;
sym_helper::analyse_matrix(is_approx_sym, is_approx_sympd, A);
do_sym = ((is_cx<eT>::no) ? (is_approx_sym) : (is_approx_sym && is_approx_sympd));
}
if(do_sym)
{
arma_extra_debug_print("op_pinv: symmetric/hermitian optimisation");
return op_pinv::apply_sym(out, A, tol, method_id);
}
return op_pinv::apply_gen(out, A, tol, method_id);
}
template<typename eT>
inline
bool
op_pinv::apply_diag(Mat<eT>& out, const Mat<eT>& A, typename get_pod_type<eT>::result tol)
{
arma_extra_debug_sigprint();
typedef typename get_pod_type<eT>::result T;
out.zeros(A.n_cols, A.n_rows);
const uword N = (std::min)(A.n_rows, A.n_cols);
podarray<T> diag_abs_vals(N);
T max_abs_Aii = T(0);
for(uword i=0; i<N; ++i)
{
const eT Aii = A.at(i,i);
const T abs_Aii = std::abs(Aii);
if(arma_isnan(Aii)) { return false; }
diag_abs_vals[i] = abs_Aii;
max_abs_Aii = (abs_Aii > max_abs_Aii) ? abs_Aii : max_abs_Aii;
}
if(tol == T(0)) { tol = (std::max)(A.n_rows, A.n_cols) * max_abs_Aii * std::numeric_limits<T>::epsilon(); }
for(uword i=0; i<N; ++i)
{
if(diag_abs_vals[i] >= tol)
{
const eT Aii = A.at(i,i);
if(Aii != eT(0)) { out.at(i,i) = eT(eT(1) / Aii); }
}
}
return true;
}
template<typename eT>
inline
bool
op_pinv::apply_sym(Mat<eT>& out, const Mat<eT>& A, typename get_pod_type<eT>::result tol, const uword method_id)
{
arma_extra_debug_sigprint();
typedef typename get_pod_type<eT>::result T;
Col< T> eigval;
Mat<eT> eigvec;
const bool status = ((method_id == uword(0)) || (method_id == uword(2))) ? auxlib::eig_sym_dc(eigval, eigvec, A) : auxlib::eig_sym(eigval, eigvec, A);
if(status == false) { return false; }
if(eigval.n_elem == 0) { out.zeros(A.n_cols, A.n_rows); return true; }
Col<T> abs_eigval = arma::abs(eigval);
const uvec indices = sort_index(abs_eigval, "descend");
abs_eigval = abs_eigval.elem(indices);
eigval = eigval.elem(indices);
eigvec = eigvec.cols(indices);
// 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(); }
uword count = 0;
for(uword i=0; i < abs_eigval.n_elem; ++i) { count += (abs_eigval[i] >= tol) ? uword(1) : uword(0); }
if(count == 0) { out.zeros(A.n_cols, A.n_rows); return true; }
Col<T> eigval2(count, arma_nozeros_indicator());
uword count2 = 0;
for(uword i=0; i < eigval.n_elem; ++i)
{
const T abs_val = abs_eigval[i];
const T val = eigval[i];
if(abs_val >= tol) { eigval2[count2] = (val != T(0)) ? T(T(1) / val) : T(0); ++count2; }
}
const Mat<eT> eigvec_use(eigvec.memptr(), eigvec.n_rows, count, false);
out = (eigvec_use * diagmat(eigval2)).eval() * eigvec_use.t();
return true;
}
template<typename eT>
inline
bool
op_pinv::apply_gen(Mat<eT>& out, Mat<eT>& A, typename get_pod_type<eT>::result tol, const uword method_id)
{
arma_extra_debug_sigprint();
typedef typename get_pod_type<eT>::result T;
const uword n_rows = A.n_rows;
const uword n_cols = A.n_cols;
// economical SVD decomposition
Mat<eT> U;
Col< T> s;
Mat<eT> V;
if(n_cols > n_rows) { A = trans(A); }
const bool status = ((method_id == uword(0)) || (method_id == uword(2))) ? auxlib::svd_dc_econ(U, s, V, A) : auxlib::svd_econ(U, s, V, A, 'b');
if(status == false) { return false; }
// 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(); }
uword count = 0;
for(uword i=0; i < s.n_elem; ++i) { count += (s[i] >= tol) ? uword(1) : uword(0); }
if(count == 0) { out.zeros(n_cols, n_rows); return true; }
Col<T> s2(count, arma_nozeros_indicator());
uword count2 = 0;
for(uword i=0; i < s.n_elem; ++i)
{
const T val = s[i];
if(val >= tol) { s2[count2] = (val > T(0)) ? T(T(1) / val) : T(0); ++count2; }
}
const Mat<eT> U_use(U.memptr(), U.n_rows, count, false);
const Mat<eT> V_use(V.memptr(), V.n_rows, count, false);
Mat<eT> tmp;
if(n_rows >= n_cols)
{
// out = ( (V.n_cols > count) ? V.cols(0,count-1) : V ) * diagmat(s2) * trans( (U.n_cols > count) ? U.cols(0,count-1) : U );
tmp = V_use * diagmat(s2);
out = tmp * trans(U_use);
}
else
{
// out = ( (U.n_cols > count) ? U.cols(0,count-1) : U ) * diagmat(s2) * trans( (V.n_cols > count) ? V.cols(0,count-1) : V );
tmp = U_use * diagmat(s2);
out = tmp * trans(V_use);
}
return true;
}
//! @}