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Grid/lib/qcd/action/fermion/DomainWallFermion.h
Peter Boyle 3845f267cb Domain wall fermions now invert ; have the basis set up for
Tanh/Zolo * (Cayley/PartFrac/ContFrac) * (Mobius/Shamir/Wilson)
Approx        Representation               Kernel.

All are done with space-time taking part in checkerboarding, Ls uncheckerboarded

Have only so far tested the Domain Wall limit of mobius, and at that only checked
that it
i)  Inverts
ii) 5dim DW == Ls copies of 4dim D2
iii) MeeInv Mee == 1
iv) Meo+Mee+Moe+Moo == M unprec.
v) MpcDagMpc is hermitan
vi) Mdag is the adjoint of M between stochastic vectors.

That said, the RB schur solve, RB MpcDagMpc solve, Unprec solve
all converge and the true residual becomes small; so pretty good tests.
2015-06-02 16:57:12 +01:00

119 lines
2.7 KiB
C++

#ifndef GRID_QCD_DOMAIN_WALL_FERMION_H
#define GRID_QCD_DOMAIN_WALL_FERMION_H
#include <Grid.h>
namespace Grid {
namespace QCD {
class DomainWallFermion : public CayleyFermion5D
{
public:
// Constructors
DomainWallFermion(LatticeGaugeField &_Umu,
GridCartesian &FiveDimGrid,
GridRedBlackCartesian &FiveDimRedBlackGrid,
GridCartesian &FourDimGrid,
GridRedBlackCartesian &FourDimRedBlackGrid,
RealD _mass,RealD _M5) :
CayleyFermion5D(_Umu,
FiveDimGrid,
FiveDimRedBlackGrid,
FourDimGrid,
FourDimRedBlackGrid,_mass,_M5)
{
RealD eps = 1.0;
zdata = Approx::grid_higham(eps,this->Ls);// eps is ignored for higham
assert(zdata->n==this->Ls);
///////////////////////////////////////////////////////////
// The Cayley coeffs (unprec)
///////////////////////////////////////////////////////////
this->omega.resize(this->Ls);
this->bs.resize(this->Ls);
this->cs.resize(this->Ls);
this->as.resize(this->Ls);
for(int i=0; i < this->Ls; i++){
this->as[i] = 1.0;
this->omega[i] = ((double)zdata -> gamma[i]);
double bb=1.0;
this->bs[i] = 0.5*(bb/(this->omega[i]) + 1.0);
this->cs[i] = 0.5*(bb/(this->omega[i]) - 1.0);
}
////////////////////////////////////////////////////////
// Constants for the preconditioned matrix Cayley form
////////////////////////////////////////////////////////
this->bee.resize(this->Ls);
this->cee.resize(this->Ls);
this->beo.resize(this->Ls);
this->ceo.resize(this->Ls);
for(int i=0;i<this->Ls;i++){
this->bee[i]=as[i]*(bs[i]*(4.0-M5) +1.0);
this->cee[i]=as[i]*(1.0-cs[i]*(4.0-M5));
this->beo[i]=as[i]*bs[i];
this->ceo[i]=-as[i]*cs[i];
}
aee.resize(this->Ls);
aeo.resize(this->Ls);
for(int i=0;i<this->Ls;i++){
aee[i]=cee[i];
aeo[i]=ceo[i];
}
//////////////////////////////////////////
// LDU decomposition of eeoo
//////////////////////////////////////////
dee.resize(this->Ls);
lee.resize(this->Ls);
leem.resize(this->Ls);
uee.resize(this->Ls);
ueem.resize(this->Ls);
for(int i=0;i<this->Ls;i++){
dee[i] = bee[i];
if ( i < this->Ls-1 ) {
lee[i] =-cee[i+1]/bee[i]; // sub-diag entry on the ith column
leem[i]=this->mass*cee[this->Ls-1]/bee[0];
for(int j=0;j<i;j++) leem[i]*= aee[j]/bee[j+1];
uee[i] =-aee[i]/bee[i]; // up-diag entry on the ith row
ueem[i]=this->mass;
for(int j=1;j<=i;j++) ueem[i]*= cee[j]/bee[j];
ueem[i]*= aee[0]/bee[0];
} else {
lee[i] =0.0;
leem[i]=0.0;
uee[i] =0.0;
ueem[i]=0.0;
}
}
{
double delta_d=mass*cee[this->Ls-1];
for(int j=0;j<this->Ls-1;j++) delta_d *= cee[j]/bee[j];
dee[this->Ls-1] += delta_d;
}
}
};
}
}
#endif