Tensor_outer.h

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/*************************************************************************************
 
    Grid physics library, www.github.com/paboyle/Grid 
 
    Source file: ./lib/tensors/Tensor_outer.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_OUTER_H
#define GRID_MATH_OUTER_H
 
NAMESPACE_BEGIN(Grid);

// outerProduct Scalar x Scalar -> Scalar
//              Vector x Vector -> Matrix
template<class CC,IfComplex<CC> = 0>
accelerator_inline CC outerProduct(const CC &l, const CC& r)
{
  return l*conj(r);
}
template<class RR,IfReal<RR> = 0>
accelerator_inline RR outerProduct(const RR &l, const RR& r)
{
  return l*r;
}
 
template<class l,class r,int N> accelerator_inline
auto outerProduct (const iVector<l,N>& lhs,const iVector<r,N>& rhs) -> iMatrix<decltype(outerProduct(lhs._internal[0],rhs._internal[0])),N>
{
  typedef decltype(outerProduct(lhs._internal[0],rhs._internal[0])) ret_t;
  iMatrix<ret_t,N> ret;
  for(int c1=0;c1<N;c1++){
    for(int c2=0;c2<N;c2++){
      ret._internal[c1][c2] = outerProduct(lhs._internal[c1],rhs._internal[c2]);
  }}
  return ret;
}
 
 
template<class l,class r> accelerator_inline
auto outerProduct (const iScalar<l>& lhs,const iScalar<r>& rhs) -> iScalar<decltype(outerProduct(lhs._internal,rhs._internal))>
{
  typedef decltype(outerProduct(lhs._internal,rhs._internal)) ret_t;
  iScalar<ret_t> ret;
  ret._internal = outerProduct(lhs._internal,rhs._internal);
  return ret;
}
 
NAMESPACE_END(Grid);
 
#endif