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67 lines
2.1 KiB
C++
67 lines
2.1 KiB
C++
/*************************************************************************************
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Grid physics library, www.github.com/paboyle/Grid
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Source file: ./lib/tensors/Tensor_exp.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_EXP_H
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#define GRID_MATH_EXP_H
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#define DEFAULT_MAT_EXP 12
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namespace Grid {
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///////////////////////////////////////////////
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// Exponentiate function for scalar, vector, matrix
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///////////////////////////////////////////////
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template<class vtype> inline iScalar<vtype> Exponentiate(const iScalar<vtype>&r, ComplexD alpha , Integer Nexp = DEFAULT_MAT_EXP)
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{
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iScalar<vtype> ret;
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ret._internal = Exponentiate(r._internal, alpha, Nexp);
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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 iMatrix<vtype,N> Exponentiate(const iMatrix<vtype,N> &arg, ComplexD alpha , Integer Nexp = DEFAULT_MAT_EXP )
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{
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iMatrix<vtype,N> unit(1.0);
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iMatrix<vtype,N> temp(unit);
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for(int i=Nexp; i>=1;--i){
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temp *= alpha/ComplexD(i);
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temp = unit + temp*arg;
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}
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return temp;
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}
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}
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#endif
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