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Grid/examples/Example_Laplacian.cc
Christopher Kelly 1ad54d049d To PeriodicBC and ConjugateBC, added a new function "CshiftLink" which performs a boundary-aware C-shift of links or products of links. For the latter, the links crossing the global boundary are complex-conjugated.
To the gauge implementations, added CshiftLink functions calling into the appropriate operation for the BC in a given direction.
GaugeTransform, FourierAcceleratedGaugeFixer and WilsonLoops::FieldStrength no longer implicitly assume periodic boundary conditions; instead the shifted link is obtained using CshiftLink and is aware of the gauge implementation.
Added an assert-check to ensure that the gauge fixing converges within the specified number of steps.
Added functionality to compute the timeslice averaged plaquette
Added functionality to compute the 5LI topological charge and timeslice topological charge
Added a check of the properties of the charge conjugation matrix C=-gamma_2 gamma_4 to Test_gamma
Fixed const correctness for Replicate
Modified Test_fft_gfix to support either conjugate or periodic BCs, optionally disabling Fourier-accelerated gauge fixing, and tuning of alpha using cmdline options
2022-06-02 15:30:41 -04:00

397 lines
14 KiB
C++

#include <Grid/Grid.h>
using namespace Grid;
/*
/////////////////////////////////////////////////////////////////////////////////////////////
// Grid/algorithms/SparseMatrix.h: Interface defining what I expect of a general sparse matrix, such as a Fermion action
/////////////////////////////////////////////////////////////////////////////////////////////
template<class Field> class SparseMatrixBase {
public:
virtual GridBase *Grid(void) =0;
virtual void M (const Field &in, Field &out)=0;
virtual void Mdag (const Field &in, Field &out)=0;
virtual void MdagM(const Field &in, Field &out) {
Field tmp (in.Grid());
M(in,tmp);
Mdag(tmp,out);
}
virtual void Mdiag (const Field &in, Field &out)=0;
virtual void Mdir (const Field &in, Field &out,int dir, int disp)=0;
virtual void MdirAll (const Field &in, std::vector<Field> &out)=0;
};
*/
const std::vector<int> directions ({Xdir,Ydir,Zdir,Xdir,Ydir,Zdir});
const std::vector<int> displacements({1,1,1,-1,-1,-1});
template<class Field> class FreeLaplacianCshift : public SparseMatrixBase<Field>
{
public:
GridBase *grid;
FreeLaplacianCshift(GridBase *_grid)
{
grid=_grid;
};
virtual GridBase *Grid(void) { return grid; };
virtual void M (const Field &in, Field &out)
{
out = Zero();
for(int mu=0;mu<Nd-1;mu++) {
out = out + Cshift(in,mu,1) + Cshift(in,mu,-1) - 2.0 * in;
}
};
virtual void Mdag (const Field &in, Field &out) { M(in,out);}; // Laplacian is hermitian
virtual void Mdiag (const Field &in, Field &out) {assert(0);}; // Unimplemented need only for multigrid
virtual void Mdir (const Field &in, Field &out,int dir, int disp){assert(0);}; // Unimplemented need only for multigrid
virtual void MdirAll (const Field &in, std::vector<Field> &out) {assert(0);}; // Unimplemented need only for multigrid
};
template<class Gimpl,class Field> class CovariantLaplacianCshift : public SparseMatrixBase<Field>
{
public:
INHERIT_GIMPL_TYPES(Gimpl);
GridBase *grid;
GaugeField U;
CovariantLaplacianCshift(GaugeField &_U) :
grid(_U.Grid()),
U(_U) { };
virtual GridBase *Grid(void) { return grid; };
virtual void M (const Field &in, Field &out)
{
out=Zero();
for(int mu=0;mu<Nd-1;mu++) {
GaugeLinkField Umu = PeekIndex<LorentzIndex>(U, mu); // NB: Inefficent
out = out + Gimpl::CovShiftForward(Umu,mu,in);
out = out + Gimpl::CovShiftBackward(Umu,mu,in);
out = out - 2.0*in;
}
};
virtual void Mdag (const Field &in, Field &out) { M(in,out);}; // Laplacian is hermitian
virtual void Mdiag (const Field &in, Field &out) {assert(0);}; // Unimplemented need only for multigrid
virtual void Mdir (const Field &in, Field &out,int dir, int disp){assert(0);}; // Unimplemented need only for multigrid
virtual void MdirAll (const Field &in, std::vector<Field> &out) {assert(0);}; // Unimplemented need only for multigrid
};
#define LEG_LOAD(Dir) \
SE = st.GetEntry(ptype, Dir, ss); \
if (SE->_is_local ) { \
int perm= SE->_permute; \
chi = coalescedReadPermute(in[SE->_offset],ptype,perm,lane); \
} else { \
chi = coalescedRead(buf[SE->_offset],lane); \
} \
acceleratorSynchronise();
template<class Field> class FreeLaplacianStencil : public SparseMatrixBase<Field>
{
public:
typedef typename Field::vector_object siteObject;
typedef CartesianStencil<siteObject, siteObject, int> StencilImpl;
GridBase *grid;
StencilImpl Stencil;
SimpleCompressor<siteObject> Compressor;
FreeLaplacianStencil(GridBase *_grid)
: Stencil (_grid,6,Even,directions,displacements,0), grid(_grid)
{ };
virtual GridBase *Grid(void) { return grid; };
virtual void M (const Field &_in, Field &_out)
{
///////////////////////////////////////////////
// Halo exchange for this geometry of stencil
///////////////////////////////////////////////
Stencil.HaloExchange(_in, Compressor);
///////////////////////////////////
// Arithmetic expressions
///////////////////////////////////
// Views; device friendly/accessible pointers
auto st = Stencil.View(AcceleratorRead);
auto buf = st.CommBuf();
autoView( in , _in , AcceleratorRead);
autoView( out , _out , AcceleratorWrite);
typedef typename Field::vector_object vobj;
typedef decltype(coalescedRead(in[0])) calcObj;
const int Nsimd = vobj::Nsimd();
const uint64_t NN = grid->oSites();
accelerator_for( ss, NN, Nsimd, {
StencilEntry *SE;
const int lane=acceleratorSIMTlane(Nsimd);
calcObj chi;
calcObj res;
int ptype;
res = coalescedRead(in[ss])*(-6.0);
LEG_LOAD(0); res = res + chi;
LEG_LOAD(1); res = res + chi;
LEG_LOAD(2); res = res + chi;
LEG_LOAD(3); res = res + chi;
LEG_LOAD(4); res = res + chi;
LEG_LOAD(5); res = res + chi;
coalescedWrite(out[ss], res,lane);
});
};
virtual void Mdag (const Field &in, Field &out) { M(in,out);}; // Laplacian is hermitian
virtual void Mdiag (const Field &in, Field &out) {assert(0);}; // Unimplemented need only for multigrid
virtual void Mdir (const Field &in, Field &out,int dir, int disp){assert(0);}; // Unimplemented need only for multigrid
virtual void MdirAll (const Field &in, std::vector<Field> &out) {assert(0);}; // Unimplemented need only for multigrid
};
template<class Gimpl,class Field> class CovariantLaplacianStencil : public SparseMatrixBase<Field>
{
public:
INHERIT_GIMPL_TYPES(Gimpl);
typedef typename Field::vector_object siteObject;
template <typename vtype> using iImplDoubledGaugeField = iVector<iScalar<iMatrix<vtype, Nc> >, Nds>;
typedef iImplDoubledGaugeField<Simd> SiteDoubledGaugeField;
typedef Lattice<SiteDoubledGaugeField> DoubledGaugeField;
typedef CartesianStencil<siteObject, siteObject, int> StencilImpl;
GridBase *grid;
StencilImpl Stencil;
SimpleCompressor<siteObject> Compressor;
DoubledGaugeField Uds;
CovariantLaplacianStencil(GaugeField &Umu)
:
grid(Umu.Grid()),
Stencil (grid,6,Even,directions,displacements,0),
Uds(grid)
{
for (int mu = 0; mu < Nd; mu++) {
auto U = PeekIndex<LorentzIndex>(Umu, mu);
PokeIndex<LorentzIndex>(Uds, U, mu );
U = adj(Cshift(U, mu, -1));
PokeIndex<LorentzIndex>(Uds, U, mu + 4);
}
};
virtual GridBase *Grid(void) { return grid; };
virtual void M (const Field &_in, Field &_out)
{
///////////////////////////////////////////////
// Halo exchange for this geometry of stencil
///////////////////////////////////////////////
Stencil.HaloExchange(_in, Compressor);
///////////////////////////////////
// Arithmetic expressions
///////////////////////////////////
auto st = Stencil.View(AcceleratorRead);
auto buf = st.CommBuf();
autoView( in , _in , AcceleratorRead);
autoView( out , _out , AcceleratorWrite);
autoView( U , Uds , AcceleratorRead);
typedef typename Field::vector_object vobj;
typedef decltype(coalescedRead(in[0])) calcObj;
typedef decltype(coalescedRead(U[0](0))) calcLink;
const int Nsimd = vobj::Nsimd();
const uint64_t NN = grid->oSites();
accelerator_for( ss, NN, Nsimd, {
StencilEntry *SE;
const int lane=acceleratorSIMTlane(Nsimd);
calcObj chi;
calcObj res;
calcObj Uchi;
calcLink UU;
int ptype;
res = coalescedRead(in[ss])*(-6.0);
#define LEG_LOAD_MULT(leg,polarisation) \
UU = coalescedRead(U[ss](polarisation)); \
LEG_LOAD(leg); \
mult(&Uchi(), &UU, &chi()); \
res = res + Uchi;
LEG_LOAD_MULT(0,Xp);
LEG_LOAD_MULT(1,Yp);
LEG_LOAD_MULT(2,Zp);
LEG_LOAD_MULT(3,Xm);
LEG_LOAD_MULT(4,Ym);
LEG_LOAD_MULT(5,Zm);
coalescedWrite(out[ss], res,lane);
});
};
virtual void Mdag (const Field &in, Field &out) { M(in,out);}; // Laplacian is hermitian
virtual void Mdiag (const Field &in, Field &out) {assert(0);}; // Unimplemented need only for multigrid
virtual void Mdir (const Field &in, Field &out,int dir, int disp){assert(0);}; // Unimplemented need only for multigrid
virtual void MdirAll (const Field &in, std::vector<Field> &out) {assert(0);}; // Unimplemented need only for multigrid
};
#undef LEG_LOAD_MULT
#undef LEG_LOAD
int main(int argc, char ** argv)
{
Grid_init(&argc, &argv);
typedef LatticeColourVector Field;
auto latt_size = GridDefaultLatt();
auto simd_layout = GridDefaultSimd(Nd,vComplex::Nsimd());
auto mpi_layout = GridDefaultMpi();
GridCartesian Grid(latt_size,simd_layout,mpi_layout);
GridParallelRNG RNG(&Grid); RNG.SeedFixedIntegers(std::vector<int>({45,12,81,9}));
FreeLaplacianCshift<Field> FLcs(&Grid);
FreeLaplacianStencil<Field> FLst(&Grid);
LatticeGaugeField U(&Grid);
SU<Nc>::ColdConfiguration(RNG,U);
std::cout << " Gauge field has norm " <<norm2(U)<<std::endl;
CovariantLaplacianCshift <PeriodicGimplR,Field> CLcs(U);
CovariantLaplacianStencil<PeriodicGimplR,Field> CLst(U);
Field in(&Grid); gaussian(RNG,in);
Field out_FLcs(&Grid);
Field out_FLst(&Grid);
Field out_CLcs(&Grid);
Field out_CLst(&Grid);
Field diff(&Grid);
////////////////////////////////////////////////////////
// First test: in free field these should all agree
////////////////////////////////////////////////////////
FLcs.M(in,out_FLcs);
FLst.M(in,out_FLst);
CLcs.M(in,out_CLcs);
CLst.M(in,out_CLst);
std:: cout << "******************************************************************" <<std::endl;
std:: cout << " Test A: consistency of four different Laplacian implementations " <<std::endl;
std:: cout << "******************************************************************" <<std::endl;
std:: cout << " Input test vector " <<norm2(in)<<std::endl;
std:: cout << "--------------------------------------------------------" <<std::endl;
std:: cout << " Free cshift output vector " <<norm2(out_FLcs)<<std::endl;
std:: cout << " Free stencil output vector " <<norm2(out_FLst)<<std::endl;
std:: cout << " Cov cshift output vector " <<norm2(out_CLcs)<<std::endl;
std:: cout << " Cov stencil output vector " <<norm2(out_CLst)<<std::endl;
std:: cout << "--------------------------------------------------------" <<std::endl;
diff = out_FLcs - out_FLst;
std:: cout << " Difference between free Cshift Laplacian and free Stencil Laplacian = " <<norm2(diff)<<std::endl;
diff = out_FLcs - out_CLcs;
std:: cout << " Difference between free Cshift Laplacian and covariant Cshift Laplacian = " <<norm2(diff)<<std::endl;
diff = out_FLcs - out_CLst;
std:: cout << " Difference between free Cshift Laplacian and covariant Stencil Laplacian = " <<norm2(diff)<<std::endl;
std:: cout << "--------------------------------------------------------" <<std::endl;
std:: cout << "******************************************************************" <<std::endl;
std:: cout << " Test B: gauge covariance " <<std::endl;
std:: cout << "******************************************************************" <<std::endl;
LatticeGaugeField U_GT(&Grid); // Gauge transformed field
LatticeColourMatrix g(&Grid); // local Gauge xform matrix
U_GT = U;
// Make a random xform to teh gauge field
SU<Nc>::RandomGaugeTransform<PeriodicGimplR>(RNG,U_GT,g); // Unit gauge
Field in_GT(&Grid);
Field out_GT(&Grid);
Field out_CLcs_GT(&Grid);
Field out_CLst_GT(&Grid);
CovariantLaplacianCshift <PeriodicGimplR,Field> CLcs_GT(U_GT);
CovariantLaplacianStencil<PeriodicGimplR,Field> CLst_GT(U_GT);
in_GT = g*in;
out_GT = g*out_FLcs;
// Check M^GT_xy in_GT = g(x) M_xy g^dag(y) g(y) in = g(x) out(x)
CLcs_GT.M(in_GT,out_CLcs_GT);
CLst_GT.M(in_GT,out_CLst_GT);
diff = out_CLcs_GT - out_GT;
std:: cout << " Difference between Gauge xformed result and covariant Cshift Laplacian in xformed gauge = " <<norm2(diff)<<std::endl;
diff = out_CLst_GT - out_GT;
std:: cout << " Difference between Gauge xformed result and covariant Stencil Laplacian in xformed gauge = " <<norm2(diff)<<std::endl;
std:: cout << "--------------------------------------------------------" <<std::endl;
std:: cout << "******************************************************************" <<std::endl;
std:: cout << " Test C: compare in free Field to \"Feynman rule\" " <<std::endl;
std:: cout << "******************************************************************" <<std::endl;
std::vector<int> dim_mask({1,1,1,0}); // 3d FFT
FFT theFFT(&Grid);
Field out(&Grid);
Field F_out(&Grid);
Field F_in(&Grid);
// FFT the random input vector
theFFT.FFT_dim_mask(F_in,in,dim_mask,FFT::forward);
// Convolution theorem: multiply by Fourier representation of (discrete) Laplacian to apply diff op
LatticeComplexD lap(&Grid); lap = Zero();
LatticeComplexD kmu(&Grid);
ComplexD ci(0.0,1.0);
for(int mu=0;mu<3;mu++) {
RealD TwoPiL = M_PI * 2.0/ latt_size[mu];
LatticeCoordinate(kmu,mu);
kmu = TwoPiL * kmu;
// (e^ik_mu + e^-ik_mu - 2) = 2( cos kmu - 1) ~ 2 (1 - k_mu^2/2 -1 ) = - k_mu^2 + O(k^4)
lap = lap + 2.0*cos(kmu) - 2.0;
}
F_out = lap * F_in;
// Inverse FFT the result
theFFT.FFT_dim_mask(out,F_out,dim_mask,FFT::backward);
std::cout<<"Fourier xformed (in) "<<norm2(F_in)<<std::endl;
std::cout<<"Fourier xformed Laplacian x (in) "<<norm2(F_out)<<std::endl;
std::cout<<"Momentum space Laplacian application "<< norm2(out)<<std::endl;
std::cout<<"Stencil Laplacian application "<< norm2(out_CLcs)<<std::endl;
diff = out_CLcs - out;
std::cout<<"diff "<< norm2(diff)<<std::endl;
Grid_finalize();
}