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/* -*- c++ -*- (enables emacs c++ mode) */
/*===========================================================================
Copyright (C) 2003-2015 Yves Renard
This file is a part of GETFEM++
Getfem++ is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version along with the GCC Runtime Library
Exception either version 3.1 or (at your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License and GCC Runtime Library Exception for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
As a special exception, you may use this file as it is a part of a free
software library without restriction. Specifically, if other files
instantiate templates or use macros or inline functions from this file,
or you compile this file and link it with other files to produce an
executable, this file does not by itself cause the resulting executable
to be covered by the GNU Lesser General Public License. This exception
does not however invalidate any other reasons why the executable file
might be covered by the GNU Lesser General Public License.
===========================================================================*/
/**@file gmm_precond_diagonal.h
@author Yves Renard <Yves.Renard@insa-lyon.fr>
@date June 5, 2003.
@brief Diagonal matrix preconditoner.
*/
#ifndef GMM_PRECOND_DIAGONAL_H
#define GMM_PRECOND_DIAGONAL_H
#include "gmm_precond.h"
namespace gmm {
/** Diagonal preconditioner. */
template<typename Matrix> struct diagonal_precond {
typedef typename linalg_traits<Matrix>::value_type value_type;
typedef typename number_traits<value_type>::magnitude_type magnitude_type;
std::vector<magnitude_type> diag;
void build_with(const Matrix &M) {
diag.resize(mat_nrows(M));
for (size_type i = 0; i < mat_nrows(M); ++i) {
magnitude_type x = gmm::abs(M(i, i));
if (x == magnitude_type(0)) {
x = magnitude_type(1);
GMM_WARNING2("The matrix has a zero on its diagonal");
}
diag[i] = magnitude_type(1) / x;
}
}
size_type memsize() const { return sizeof(*this) + diag.size() * sizeof(value_type); }
diagonal_precond(const Matrix &M) { build_with(M); }
diagonal_precond(void) {}
};
template <typename Matrix, typename V2> inline
void mult_diag_p(const diagonal_precond<Matrix>& P, V2 &v2, abstract_sparse){
typename linalg_traits<V2>::iterator it = vect_begin(v2),
ite = vect_end(v2);
for (; it != ite; ++it) *it *= P.diag[it.index()];
}
template <typename Matrix, typename V2> inline
void mult_diag_p(const diagonal_precond<Matrix>& P,V2 &v2, abstract_skyline)
{ mult_diag_p(P, v2, abstract_sparse()); }
template <typename Matrix, typename V2> inline
void mult_diag_p(const diagonal_precond<Matrix>& P, V2 &v2, abstract_dense){
for (size_type i = 0; i < P.diag.size(); ++i) v2[i] *= P.diag[i];
}
template <typename Matrix, typename V1, typename V2> inline
void mult(const diagonal_precond<Matrix>& P, const V1 &v1, V2 &v2) {
GMM_ASSERT2(P.diag.size() == vect_size(v2),"dimensions mismatch");
copy(v1, v2);
mult_diag_p(P, v2, typename linalg_traits<V2>::storage_type());
}
template <typename Matrix, typename V1, typename V2> inline
void transposed_mult(const diagonal_precond<Matrix>& P,const V1 &v1,V2 &v2) {
mult(P, v1, v2);
}
// # define DIAG_LEFT_MULT_SQRT
template <typename Matrix, typename V1, typename V2> inline
void left_mult(const diagonal_precond<Matrix>& P, const V1 &v1, V2 &v2) {
GMM_ASSERT2(P.diag.size() == vect_size(v2), "dimensions mismatch");
copy(v1, v2);
# ifdef DIAG_LEFT_MULT_SQRT
for (size_type i= 0; i < P.diag.size(); ++i) v2[i] *= gmm::sqrt(P.diag[i]);
# else
for (size_type i= 0; i < P.diag.size(); ++i) v2[i] *= P.diag[i];
# endif
}
template <typename Matrix, typename V1, typename V2> inline
void transposed_left_mult(const diagonal_precond<Matrix>& P,
const V1 &v1, V2 &v2)
{ left_mult(P, v1, v2); }
template <typename Matrix, typename V1, typename V2> inline
void right_mult(const diagonal_precond<Matrix>& P, const V1 &v1, V2 &v2) {
// typedef typename linalg_traits<Matrix>::value_type T;
GMM_ASSERT2(P.diag.size() == vect_size(v2), "dimensions mismatch");
copy(v1, v2);
# ifdef DIAG_LEFT_MULT_SQRT
for (size_type i= 0; i < P.diag.size(); ++i) v2[i] *= gmm::sqrt(P.diag[i]);
# endif
}
template <typename Matrix, typename V1, typename V2> inline
void transposed_right_mult(const diagonal_precond<Matrix>& P,
const V1 &v1, V2 &v2)
{ right_mult(P, v1, v2); }
}
#endif