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armadillo-code/include/armadillo_bits/op_logmat_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_logmat
//! @{
// Partly based on algorithm 11.9 (inverse scaling and squaring algorithm with Schur decomposition) in:
// Nicholas J. Higham.
// Functions of Matrices: Theory and Computation.
// SIAM, 2008.
// ISBN 978-0-89871-646-7
template<typename T1>
inline
void
op_logmat::apply(Mat< std::complex<typename T1::elem_type> >& out, const mtOp<std::complex<typename T1::elem_type>,T1,op_logmat>& in)
{
arma_debug_sigprint();
const bool status = op_logmat::apply_direct(out, in.m, in.aux_uword_a);
if(status == false)
{
out.soft_reset();
arma_stop_runtime_error("logmat(): transformation failed");
}
}
template<typename T1>
inline
bool
op_logmat::apply_direct(Mat< std::complex<typename T1::elem_type> >& out, const Op<T1,op_diagmat>& expr, const uword)
{
arma_debug_sigprint();
typedef typename T1::elem_type T;
const diagmat_proxy<T1> P(expr.m);
arma_conform_check( (P.n_rows != P.n_cols), "logmat(): given matrix must be square sized" );
const uword N = P.n_rows;
out.zeros(N,N); // aliasing can't happen as op_logmat is defined as cx_mat = op(mat)
for(uword i=0; i<N; ++i)
{
const T val = P[i];
if(val >= T(0))
{
out.at(i,i) = std::log(val);
}
else
{
out.at(i,i) = std::log( std::complex<T>(val) );
}
}
return true;
}
template<typename T1>
inline
bool
op_logmat::apply_direct(Mat< std::complex<typename T1::elem_type> >& out, const Base<typename T1::elem_type,T1>& expr, const uword n_iters)
{
arma_debug_sigprint();
typedef typename T1::elem_type in_T;
typedef typename std::complex<in_T> out_T;
const quasi_unwrap<T1> expr_unwrap(expr.get_ref());
const Mat<in_T>& A = expr_unwrap.M;
arma_conform_check( (A.is_square() == false), "logmat(): given matrix must be square sized" );
if(A.n_elem == 0)
{
out.reset();
return true;
}
else
if(A.n_elem == 1)
{
out.set_size(1,1);
out[0] = std::log( std::complex<in_T>( A[0] ) );
return true;
}
if(A.is_diagmat())
{
arma_debug_print("op_logmat: diag optimisation");
const uword N = A.n_rows;
out.zeros(N,N); // aliasing can't happen as op_logmat is defined as cx_mat = op(mat)
for(uword i=0; i<N; ++i)
{
const in_T val = A.at(i,i);
if(val >= in_T(0))
{
out.at(i,i) = std::log(val);
}
else
{
out.at(i,i) = std::log( out_T(val) );
}
}
return true;
}
const bool try_sympd = arma_config::optimise_sym && sym_helper::guess_sympd(A);
if(try_sympd)
{
arma_debug_print("op_logmat: attempting sympd optimisation");
// if matrix A is sympd, all its eigenvalues are positive
Col<in_T> eigval;
Mat<in_T> eigvec;
const bool eig_status = eig_sym_helper(eigval, eigvec, A, 'd', "logmat()");
if(eig_status)
{
// ensure each eigenvalue is > 0
const uword N = eigval.n_elem;
const in_T* eigval_mem = eigval.memptr();
bool all_pos = true;
for(uword i=0; i<N; ++i) { all_pos = (eigval_mem[i] <= in_T(0)) ? false : all_pos; }
if(all_pos)
{
eigval = log(eigval);
out = conv_to< Mat<out_T> >::from( eigvec * diagmat(eigval) * eigvec.t() );
return true;
}
}
arma_debug_print("op_logmat: sympd optimisation failed");
// fallthrough if eigen decomposition failed or an eigenvalue is <= 0
}
Mat<out_T> S(A.n_rows, A.n_cols, arma_nozeros_indicator());
const in_T* Amem = A.memptr();
out_T* Smem = S.memptr();
const uword n_elem = A.n_elem;
for(uword i=0; i<n_elem; ++i)
{
Smem[i] = std::complex<in_T>( Amem[i] );
}
return op_logmat_cx::apply_common(out, S, n_iters);
}
template<typename T1>
inline
void
op_logmat_cx::apply(Mat<typename T1::elem_type>& out, const Op<T1,op_logmat_cx>& in)
{
arma_debug_sigprint();
const bool status = op_logmat_cx::apply_direct(out, in.m, in.aux_uword_a);
if(status == false)
{
out.soft_reset();
arma_stop_runtime_error("logmat(): transformation failed");
}
}
template<typename T1>
inline
bool
op_logmat_cx::apply_direct(Mat<typename T1::elem_type>& out, const Op<T1,op_diagmat>& expr, const uword)
{
arma_debug_sigprint();
typedef typename T1::elem_type eT;
const diagmat_proxy<T1> P(expr.m);
bool status = false;
if(P.is_alias(out))
{
Mat<eT> tmp;
status = op_logmat_cx::apply_direct_noalias(tmp, P);
out.steal_mem(tmp);
}
else
{
status = op_logmat_cx::apply_direct_noalias(out, P);
}
return status;
}
template<typename T1>
inline
bool
op_logmat_cx::apply_direct_noalias(Mat<typename T1::elem_type>& out, const diagmat_proxy<T1>& P)
{
arma_debug_sigprint();
arma_conform_check( (P.n_rows != P.n_cols), "logmat(): given matrix must be square sized" );
const uword N = P.n_rows;
out.zeros(N,N);
for(uword i=0; i<N; ++i)
{
out.at(i,i) = std::log(P[i]);
}
return true;
}
template<typename T1>
inline
bool
op_logmat_cx::apply_direct(Mat<typename T1::elem_type>& out, const Base<typename T1::elem_type,T1>& expr, const uword n_iters)
{
arma_debug_sigprint();
typedef typename T1::pod_type T;
typedef typename T1::elem_type eT;
Mat<eT> S = expr.get_ref();
arma_conform_check( (S.n_rows != S.n_cols), "logmat(): given matrix must be square sized" );
if(S.n_elem == 0)
{
out.reset();
return true;
}
else
if(S.n_elem == 1)
{
out.set_size(1,1);
out[0] = std::log(S[0]);
return true;
}
if(S.is_diagmat())
{
arma_debug_print("op_logmat_cx: diag optimisation");
const uword N = S.n_rows;
out.zeros(N,N); // aliasing can't happen as S is generated
for(uword i=0; i<N; ++i) { out.at(i,i) = std::log( S.at(i,i) ); }
return true;
}
const bool try_sympd = arma_config::optimise_sym && sym_helper::guess_sympd(S);
if(try_sympd)
{
arma_debug_print("op_logmat_cx: attempting sympd optimisation");
// if matrix S is sympd, all its eigenvalues are positive
Col< T> eigval;
Mat<eT> eigvec;
const bool eig_status = eig_sym_helper(eigval, eigvec, S, 'd', "logmat()");
if(eig_status)
{
// ensure each eigenvalue is > 0
const uword N = eigval.n_elem;
const T* eigval_mem = eigval.memptr();
bool all_pos = true;
for(uword i=0; i<N; ++i) { all_pos = (eigval_mem[i] <= T(0)) ? false : all_pos; }
if(all_pos)
{
eigval = log(eigval);
out = eigvec * diagmat(eigval) * eigvec.t();
return true;
}
}
arma_debug_print("op_logmat_cx: sympd optimisation failed");
// fallthrough if eigen decomposition failed or an eigenvalue is <= 0
}
return op_logmat_cx::apply_common(out, S, n_iters);
}
template<typename T>
inline
bool
op_logmat_cx::apply_common(Mat< std::complex<T> >& out, Mat< std::complex<T> >& S, const uword n_iters)
{
arma_debug_sigprint();
typedef typename std::complex<T> eT;
Mat<eT> U;
const bool schur_ok = auxlib::schur(U,S);
if(schur_ok == false) { arma_debug_print("logmat(): schur decomposition failed"); return false; }
// NOTE: theta[0] and theta[1] not really used
double theta[] = { 1.10e-5, 1.82e-3, 1.6206284795015624e-2, 5.3873532631381171e-2, 1.1352802267628681e-1, 1.8662860613541288e-1, 2.642960831111435e-1 };
const uword N = S.n_rows;
uword p = 0;
uword m = 6;
uword iter = 0;
while(iter < n_iters)
{
const T tau = norm( (S - eye< Mat<eT> >(N,N)), 1 );
if(tau <= theta[6])
{
p++;
uword j1 = 0;
uword j2 = 0;
for(uword i=2; i<=6; ++i) { if( tau <= theta[i]) { j1 = i; break; } }
for(uword i=2; i<=6; ++i) { if((tau/2.0) <= theta[i]) { j2 = i; break; } }
// sanity check, for development purposes only
arma_conform_check( (j2 > j1), "internal error: op_logmat::apply_direct(): j2 > j1" );
if( ((j1 - j2) <= 1) || (p == 2) ) { m = j1; break; }
}
const bool sqrtmat_ok = op_sqrtmat_cx::apply_direct(S,S);
if(sqrtmat_ok == false) { arma_debug_print("logmat(): sqrtmat() failed"); return false; }
iter++;
}
if(iter >= n_iters) { arma_warn(2, "logmat(): reached max iterations without full convergence"); }
S.diag() -= eT(1);
if(m >= 1)
{
const bool helper_ok = op_logmat_cx::helper(S,m);
if(helper_ok == false) { return false; }
}
out = U * S * U.t();
out *= eT(eop_aux::pow(double(2), double(iter)));
return true;
}
template<typename eT>
inline
bool
op_logmat_cx::helper(Mat<eT>& A, const uword m)
{
arma_debug_sigprint();
if(A.internal_has_nonfinite()) { return false; }
const vec indices = regspace<vec>(1,m-1);
mat tmp(m, m, arma_zeros_indicator());
tmp.diag(-1) = indices / sqrt(square(2.0*indices) - 1.0);
tmp.diag(+1) = indices / sqrt(square(2.0*indices) - 1.0);
vec eigval;
mat eigvec;
const bool eig_ok = eig_sym_helper(eigval, eigvec, tmp, 'd', "logmat()");
if(eig_ok == false) { arma_debug_print("logmat(): eig_sym() failed"); return false; }
const vec nodes = (eigval + 1.0) / 2.0;
const vec weights = square(eigvec.row(0).t());
const uword N = A.n_rows;
Mat<eT> B(N, N, arma_zeros_indicator());
Mat<eT> X;
for(uword i=0; i < m; ++i)
{
// B += weights(i) * solve( (nodes(i)*A + eye< Mat<eT> >(N,N)), A );
//const bool solve_ok = solve( X, (nodes(i)*A + eye< Mat<eT> >(N,N)), A, solve_opts::fast );
const bool solve_ok = solve( X, trimatu(nodes(i)*A + eye< Mat<eT> >(N,N)), A, solve_opts::no_approx );
if(solve_ok == false) { arma_debug_print("logmat(): solve() failed"); return false; }
B += weights(i) * X;
}
A = B;
return true;
}
template<typename T1>
inline
void
op_logmat_sympd::apply(Mat<typename T1::elem_type>& out, const Op<T1,op_logmat_sympd>& in)
{
arma_debug_sigprint();
const bool status = op_logmat_sympd::apply_direct(out, in.m);
if(status == false)
{
out.soft_reset();
arma_stop_runtime_error("logmat_sympd(): transformation failed");
}
}
template<typename T1>
inline
bool
op_logmat_sympd::apply_direct(Mat<typename T1::elem_type>& out, const Base<typename T1::elem_type,T1>& expr)
{
arma_debug_sigprint();
#if defined(ARMA_USE_LAPACK)
{
typedef typename T1::pod_type T;
typedef typename T1::elem_type eT;
const unwrap<T1> U(expr.get_ref());
const Mat<eT>& X = U.M;
arma_conform_check( (X.is_square() == false), "logmat_sympd(): given matrix must be square sized" );
if((arma_config::check_conform) && (arma_config::warn_level > 0) && (is_cx<eT>::yes) && (sym_helper::check_diag_imag(X) == false))
{
arma_warn(1, "logmat_sympd(): imaginary components on diagonal are non-zero");
}
if(is_op_diagmat<T1>::value || X.is_diagmat())
{
arma_debug_print("op_logmat_sympd: diag optimisation");
out = X;
eT* colmem = out.memptr();
const uword N = X.n_rows;
for(uword i=0; i<N; ++i)
{
eT& out_ii = colmem[i];
T out_ii_real = access::tmp_real(out_ii);
if(out_ii_real <= T(0)) { return false; }
out_ii = std::log(out_ii);
colmem += N;
}
return true;
}
Col< T> eigval;
Mat<eT> eigvec;
const bool status = eig_sym_helper(eigval, eigvec, X, 'd', "logmat_sympd()");
if(status == false) { return false; }
const uword N = eigval.n_elem;
const T* eigval_mem = eigval.memptr();
bool all_pos = true;
for(uword i=0; i<N; ++i) { all_pos = (eigval_mem[i] <= T(0)) ? false : all_pos; }
if(all_pos == false) { return false; }
eigval = log(eigval);
out = eigvec * diagmat(eigval) * eigvec.t();
return true;
}
#else
{
arma_ignore(out);
arma_ignore(expr);
arma_stop_logic_error("logmat_sympd(): use of LAPACK must be enabled");
return false;
}
#endif
}
//! @}