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Grid/tests/lexLattice/Test_GaugeAction_lex.cc
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2026-08-19 20:33:10 -04:00

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/*************************************************************************************
Grid physics library, www.github.com/paboyle/Grid
Source file: ./tests/lexLattice/Test_GaugeAction_lex.cc
Copyright (C) 2026
Author: Peter Boyle <pboyle@bnl.gov>
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 */
//
// Wilson loops on a lexicographic gauge field.
//
// The configuration is generated on the vectorised grid, written as NERSC,
// and read back into the lexicographic layout: the reader recomputes the
// plaquette and link trace and checks them against the header written by
// the vectorised chart, so the crossing is validated inside Grid's own IO.
// Plaquette, link trace, rectangle and the staple identity are then compared
// between the two charts.
//
#include <Grid/Grid.h>
using namespace Grid;
const RealD tol = 1.0e-10;
int main (int argc, char ** argv)
{
Grid_init(&argc,&argv);
typedef WilsonLoops<PeriodicGimplD> vWL;
typedef WilsonLoops<lexPeriodicGimplD> lexWL;
Coordinate latt = GridDefaultLatt();
Coordinate vsimd = GridDefaultSimd(Nd,vComplexD::Nsimd());
Coordinate lsimd({1,1,1,1});
Coordinate mpi = GridDefaultMpi();
GridCartesian vGrid(latt,vsimd,mpi);
GridCartesian lGrid(latt,lsimd,mpi);
std::cout << GridLogMessage << "vectorised Nsimd = " << vGrid.Nsimd() << std::endl;
std::cout << GridLogMessage << "lexicographic Nsimd = " << lGrid.Nsimd() << std::endl;
GRID_ASSERT( lGrid.Nsimd() == 1 );
GridParallelRNG pRNG(&vGrid);
pRNG.SeedFixedIntegers(std::vector<int>({1,2,3,4}));
LatticeGaugeFieldD Umu(&vGrid);
SU<Nc>::HotConfiguration(pRNG,Umu);
std::string file("./ckpoint_lex.4000");
NerscIO::writeConfiguration(Umu,file,0,0);
lexLatticeGaugeFieldD Ulex(&lGrid);
FieldMetaData header;
NerscIO::readConfiguration(Ulex,header,file);
//////////////////////////////////////////////////
// Plaquette, link trace, rectangle in both charts
//////////////////////////////////////////////////
RealD vplaq = vWL::avgPlaquette(Umu);
RealD lplaq = lexWL::avgPlaquette(Ulex);
RealD vlink = vWL::linkTrace(Umu);
RealD llink = lexWL::linkTrace(Ulex);
RealD vrect = vWL::avgRectangle(Umu);
RealD lrect = lexWL::avgRectangle(Ulex);
std::cout << GridLogMessage << "plaquette simd " << vplaq << " lex " << lplaq
<< " header " << header.plaquette << std::endl;
std::cout << GridLogMessage << "link trace simd " << vlink << " lex " << llink
<< " header " << header.link_trace << std::endl;
std::cout << GridLogMessage << "rectangle simd " << vrect << " lex " << lrect << std::endl;
GRID_ASSERT( fabs(vplaq-lplaq) < tol );
GRID_ASSERT( fabs(vlink-llink) < tol );
GRID_ASSERT( fabs(vrect-lrect) < tol );
//////////////////////////////////////////////////
// Plaquette via staples, in the lexicographic chart
//////////////////////////////////////////////////
{
RealD vol = lGrid.gSites();
RealD stap_plaq = 0.0;
lexLatticeColourMatrixD stap(&lGrid);
lexLatticeColourMatrixD Ul(&lGrid);
lexLatticeComplexD stap_tr(&lGrid);
for(int mu=0;mu<Nd;mu++){
Ul = PeekIndex<LorentzIndex>(Ulex,mu);
lexWL::Staple(stap,Ulex,mu);
stap_tr = trace(Ul*stap);
auto Ts = sum(stap_tr);
stap_plaq += real(TensorRemove(Ts));
}
RealD StapScale = 1.0/vol/6.0/Nc/4.0;
RealD plaq_from_staples = stap_plaq*StapScale;
std::cout << GridLogMessage << "plaquette via staples (lex) " << plaq_from_staples
<< " direct " << lplaq << std::endl;
GRID_ASSERT( fabs(plaq_from_staples - lplaq) < 1.0e-8 );
}
std::cout << GridLogMessage << "Test_GaugeAction_lex: ALL PASS" << std::endl;
Grid_finalize();
}