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Grid/documentation/David_notes.txt

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2023-05-11 17:35:49 +01:00
Branch: develop
Files:
Grid/lattice/PaddedCell.h -- Halo exchange
tests/Test_general_stencil.cc -- test local off axis stencil addressing
tests/debug/Test_padded_cell.cc -- test PaddedCell halo exchange and the General local stencil by computing ALL plaquettes on lattice
Functionality:
-- extend a lattice field:
Grid/lattice/PaddedCell.h
// Constructor
PaddedCell(int _depth,GridCartesian *_grid)
// Expand a field "in" to depth "d"
template<class vobj>
inline Lattice<vobj> Exchange(Lattice<vobj> &in)
// Take the "apple core" of in to a smaller local volume
template<class vobj>
inline Lattice<vobj> Extract(Lattice<vobj> &in)
-- Plaquette test:
tests/debug/Test_padded_cell.cc
/////////////////////////////////////////////////
// Create a padded cell of extra padding depth=1
/////////////////////////////////////////////////
int depth = 1;
PaddedCell Ghost(depth,&GRID);
LatticeGaugeField Ughost = Ghost.Exchange(Umu);
///// Array for the site plaquette
GridBase *GhostGrid = Ughost.Grid();
LatticeComplex gplaq(GhostGrid);
std::vector<Coordinate> shifts;
for(int mu=0;mu<Nd;mu++){
for(int nu=mu+1;nu<Nd;nu++){
// Umu(x) Unu(x+mu) Umu^dag(x+nu) Unu^dag(x)
Coordinate shift_0(Nd,0);
Coordinate shift_mu(Nd,0); shift_mu[mu]=1;
Coordinate shift_nu(Nd,0); shift_nu[nu]=1;
shifts.push_back(shift_0);
shifts.push_back(shift_mu);
shifts.push_back(shift_nu);
shifts.push_back(shift_0);
}
}
GeneralLocalStencil gStencil(GhostGrid,shifts);
gplaq=Zero();
{
autoView( gp_v , gplaq, CpuWrite);
autoView( t_v , trplaq, CpuRead);
autoView( U_v , Ughost, CpuRead);
for(int ss=0;ss<gp_v.size();ss++){
int s=0;
for(int mu=0;mu<Nd;mu++){
for(int nu=mu+1;nu<Nd;nu++){
auto SE0 = gStencil.GetEntry(s+0,ss);
auto SE1 = gStencil.GetEntry(s+1,ss);
auto SE2 = gStencil.GetEntry(s+2,ss);
auto SE3 = gStencil.GetEntry(s+3,ss);
int o0 = SE0->_offset;
int o1 = SE1->_offset;
int o2 = SE2->_offset;
int o3 = SE3->_offset;
auto U0 = U_v[o0](mu);
auto U1 = U_v[o1](nu);
auto U2 = adj(U_v[o2](mu));
auto U3 = adj(U_v[o3](nu));
gpermute(U0,SE0->_permute);
gpermute(U1,SE1->_permute);
gpermute(U2,SE2->_permute);
gpermute(U3,SE3->_permute);
gp_v[ss]() =gp_v[ss]() + trace( U0*U1*U2*U3 );
s=s+4;
}
}
}
}
cplaq = Ghost.Extract(gplaq);