Tensor_transpose.h

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/*************************************************************************************
 
    Grid physics library, www.github.com/paboyle/Grid 
 
    Source file: ./lib/tensors/Tensor_transpose.h
 
    Copyright (C) 2015
 
Author: Peter Boyle <paboyle@ph.ed.ac.uk>
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, 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 General Public License for more details.
 
    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
    See the full license in the file "LICENSE" in the top level distribution directory
*************************************************************************************/
/*  END LEGAL */
#ifndef GRID_MATH_TRANSPOSE_H
#define GRID_MATH_TRANSPOSE_H
 
NAMESPACE_BEGIN(Grid);

// Transpose all indices
 
accelerator_inline ComplexD transpose(ComplexD &rhs){  return rhs;}
accelerator_inline ComplexF transpose(ComplexF &rhs){  return rhs;}
accelerator_inline RealD transpose(RealD &rhs){  return rhs;}
accelerator_inline RealF transpose(RealF &rhs){  return rhs;}
 
template<class vtype,int N>
accelerator_inline typename std::enable_if<isGridTensor<vtype>::value, iMatrix<vtype,N> >::type 
transpose(iMatrix<vtype,N> arg)
{
  iMatrix<vtype,N> ret;
  for(int i=0;i<N;i++){
    for(int j=0;j<N;j++){
      ret._internal[i][j] = transpose(arg._internal[j][i]); // NB recurses
    }}
  return ret;
}
template<class vtype,int N>
accelerator_inline typename std::enable_if<isGridTensor<vtype>::notvalue, iMatrix<vtype,N> >::type 
transpose(iMatrix<vtype,N> arg)
{
  iMatrix<vtype,N> ret;
  for(int i=0;i<N;i++){
    for(int j=0;j<N;j++){
      ret._internal[i][j] = arg._internal[j][i]; // Stop recursion if not a tensor type
    }}
  return ret;
}
 
template<class vtype>
accelerator_inline typename std::enable_if<isGridTensor<vtype>::value, iScalar<vtype> >::type 
transpose(iScalar<vtype> arg)
{
  iScalar<vtype> ret;
  ret._internal = transpose(arg._internal); // NB recurses
  return ret;
}
 
template<class vtype>
accelerator_inline typename std::enable_if<isGridTensor<vtype>::notvalue, iScalar<vtype> >::type 
transpose(iScalar<vtype> arg)
{
  iScalar<vtype> ret;
  ret._internal = arg._internal; // NB recursion stops
  return ret;
}
 

// Transpose a specific index; instructive to compare this style of recursion termination
// to that of adj; which is easiers?
#if 0
template<int Level,class vtype,int N> accelerator_inline 
typename std::enable_if<matchGridTensorIndex<iMatrix<vtype,N>,Level>::value, iMatrix<vtype,N> >::type 
transposeIndex (const iMatrix<vtype,N> &arg)
{
  iMatrix<vtype,N> ret;
  for(int i=0;i<N;i++){
    for(int j=0;j<N;j++){
      ret._internal[i][j] = arg._internal[j][i]; 
    }}
  return ret;
}
// or not
template<int Level,class vtype,int N> accelerator_inline 
typename std::enable_if<matchGridTensorIndex<iMatrix<vtype,N>,Level>::notvalue, iMatrix<vtype,N> >::type 
transposeIndex (const iMatrix<vtype,N> &arg)
{
  iMatrix<vtype,N> ret;
  for(int i=0;i<N;i++){
    for(int j=0;j<N;j++){
      ret._internal[i][j] = transposeIndex<Level>(arg._internal[i][j]); 
    }}
  return ret;
}
template<int Level,class vtype> accelerator_inline 
typename std::enable_if<matchGridTensorIndex<iScalar<vtype>,Level>::notvalue, iScalar<vtype> >::type 
transposeIndex (const iScalar<vtype> &arg)
{
  iScalar<vtype> ret;
  ret._internal=transposeIndex<Level>(arg._internal);
  return ret;
}
template<int Level,class vtype> accelerator_inline 
typename std::enable_if<matchGridTensorIndex<iScalar<vtype>,Level>::value, iScalar<vtype> >::type 
transposeIndex (const iScalar<vtype> &arg)
{
  return arg;
}
#endif
 
NAMESPACE_END(Grid);
 
#endif