1
0
mirror of https://github.com/paboyle/Grid.git synced 2024-11-10 15:55:37 +00:00
Grid/lib/qcd/utils/CovariantCshift.h
paboyle 5a80930dd2 Charge conjugation boundary conditions for gauge fields implemented as a policy
class, changing the nature of covariant Cshifts used in
plaquettes, rectangles and staples.

As a result same code is used for the plaq and rect action independent of the BC type.

Should probably isolate the BC in a separate class that Gimpl takes as a template param.
Do the same with smearing policies.

This would then allow composition of BC with smearing etc....
2016-01-02 13:37:25 +00:00

103 lines
3.2 KiB
C++

#ifndef QCD_UTILS_COVARIANT_CSHIFT_H
#define QCD_UTILS_COVARIANT_CSHIFT_H
namespace Grid {
namespace QCD {
////////////////////////////////////////////////////////////////////////
// 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 GparityBC {
// 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
}
}
}}
#endif