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73 lines
2.5 KiB
C++
73 lines
2.5 KiB
C++
/*************************************************************************************
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Grid physics library, www.github.com/paboyle/Grid
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Source file: ./lib/tensors/Tensor_determinant.h
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Copyright (C) 2015
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Author: neo <cossu@post.kek.jp>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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See the full license in the file "LICENSE" in the top level distribution directory
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*************************************************************************************/
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/* END LEGAL */
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#ifndef GRID_MATH_DET_H
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#define GRID_MATH_DET_H
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namespace Grid {
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///////////////////////////////////////////////
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// Determinant function for scalar, vector, matrix
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///////////////////////////////////////////////
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inline ComplexF Determinant( const ComplexF &arg){ return arg;}
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inline ComplexD Determinant( const ComplexD &arg){ return arg;}
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inline RealF Determinant( const RealF &arg){ return arg;}
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inline RealD Determinant( const RealD &arg){ return arg;}
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template<class vtype> inline auto Determinant(const iScalar<vtype>&r) -> iScalar<decltype(Determinant(r._internal))>
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{
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iScalar<decltype(Determinant(r._internal))> ret;
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ret._internal = Determinant(r._internal);
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return ret;
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}
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template<class vtype,int N, typename std::enable_if< GridTypeMapper<vtype>::TensorLevel == 0 >::type * =nullptr>
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inline iScalar<vtype> Determinant(const iMatrix<vtype,N> &arg)
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{
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iMatrix<vtype,N> ret(arg);
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iScalar<vtype> det = vtype(1.0);
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/* Conversion of matrix to upper triangular */
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for(int i = 0; i < N; i++){
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for(int j = 0; j < N; j++){
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if(j>i){
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vtype ratio = ret._internal[j][i]/ret._internal[i][i];
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for(int k = 0; k < N; k++){
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ret._internal[j][k] -= ratio * ret._internal[i][k];
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}
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}
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}
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}
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for(int i = 0; i < N; i++)
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det *= ret._internal[i][i];
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return det;
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}
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}
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#endif
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