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Grid/lib/qcd/utils/CovariantCshift.h
2018-03-07 16:54:11 +00:00

130 lines
4.4 KiB
C++

/*************************************************************************************
Grid physics library, www.github.com/paboyle/Grid
Source file: ./lib/qcd/utils/CovariantCshift.h
Copyright (C) 2015
Author: Azusa Yamaguchi <ayamaguc@staffmail.ed.ac.uk>
Author: paboyle <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 QCD_UTILS_COVARIANT_CSHIFT_H
#define QCD_UTILS_COVARIANT_CSHIFT_H
NAMESPACE_BEGIN(Grid);
////////////////////////////////////////////////////////////////////////
// Low performance implementation of CovariantCshift API
////////////////////////////////////////////////////////////////////////
// Make these members of an Impl class for BC's.
namespace PeriodicBC {
template<class covariant,class gauge> Lattice<covariant> CovShiftForward(const Lattice<gauge> &Link,
int mu,
const Lattice<covariant> &field)
{
return Link*Cshift(field,mu,1);// moves towards negative mu
}
template<class covariant,class gauge> Lattice<covariant> CovShiftBackward(const Lattice<gauge> &Link,
int mu,
const Lattice<covariant> &field)
{
Lattice<covariant> tmp(field.Grid());
tmp = adj(Link)*field;
return Cshift(tmp,mu,-1);// moves towards positive mu
}
}
namespace ConjugateBC {
// Must give right answers across boundary
// <----
// --
// | |
// xxxxxxxxxxxxxxxxxxxx
// | |
//
// Stap= Cshift(GImpl::CovShiftForward(U[nu],nu,
// GImpl::CovShiftForward(U[nu],nu,
// GImpl::CovShiftBackward(U[mu],mu,
// GImpl::CovShiftBackward(U[nu],nu,
// GImpl::CovShiftIdentityBackward(U[nu],nu,-1))))) , mu, 1);
//
// U U^* U^* U^T U^adj = U (U U U^dag U^T )^*
// = U (U U U^dag)^* ( U^T )^*
//
// So covariant shift rule: Conjugate inward shifted plane when crossing boundary applies.
//
// This Conjugate should be applied to BOTH the link and the covariant field on backward shift
// boundary wrap.
//
// | |
// xxxxxxxxxxxxxxxxx
// | | <---- this link is Conjugated, and the path leading into it. Segment crossing in and out is double Conjugated.
// --
// ------->
template<class covariant,class gauge> Lattice<covariant> CovShiftForward(const Lattice<gauge> &Link,
int mu,
const Lattice<covariant> &field)
{
GridBase * grid = Link.Grid();
int Lmu = grid->GlobalDimensions()[mu]-1;
conformable(field,Link);
Lattice<iScalar<vInteger> > coor(grid); LatticeCoordinate(coor,mu);
Lattice<covariant> field_bc = Cshift(field,mu,1);// moves towards negative mu;
field_bc = where(coor==Lmu,conjugate(field_bc),field_bc);
// std::cout<<"Gparity::CovCshiftForward mu="<<mu<<std::endl;
return Link*field_bc;
}
template<class covariant,class gauge> Lattice<covariant> CovShiftBackward(const Lattice<gauge> &Link,
int mu,
const Lattice<covariant> &field)
{
GridBase * grid = field.Grid();
int Lmu = grid->GlobalDimensions()[mu]-1;
conformable(field,Link);
Lattice<iScalar<vInteger> > coor(grid); LatticeCoordinate(coor,mu);
Lattice<covariant> tmp(grid);
tmp = adj(Link)*field;
tmp = where(coor==Lmu,conjugate(tmp),tmp);
// std::cout<<"Gparity::CovCshiftBackward mu="<<mu<<std::endl;
return Cshift(tmp,mu,-1);// moves towards positive mu
}
}
NAMESPACE_END(Grid);
#endif