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Grid/lib/qcd/action/pseudofermion/OneFlavourEvenOddRationalRatio.h

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/*************************************************************************************
Grid physics library, www.github.com/paboyle/Grid
Source file: ./lib/qcd/action/pseudofermion/OneFlavourEvenOddRationalRatio.h
Copyright (C) 2015
Author: Peter Boyle <paboyle@ph.ed.ac.uk>
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 */
#ifndef QCD_PSEUDOFERMION_ONE_FLAVOUR_EVEN_ODD_RATIONAL_RATIO_H
#define QCD_PSEUDOFERMION_ONE_FLAVOUR_EVEN_ODD_RATIONAL_RATIO_H
namespace Grid{
namespace QCD{
///////////////////////////////////////
// One flavour rational
///////////////////////////////////////
// S_f = chi^dag* P(V^dag*V)/Q(V^dag*V)* N(M^dag*M)/D(M^dag*M)* P(V^dag*V)/Q(V^dag*V)* chi
//
// Here P/Q \sim R_{1/4} ~ (V^dagV)^{1/4}
// Here N/D \sim R_{-1/2} ~ (M^dagM)^{-1/2}
template<class Impl>
class OneFlavourEvenOddRatioRationalPseudoFermionAction : public Action<typename Impl::GaugeField> {
public:
INHERIT_IMPL_TYPES(Impl);
typedef OneFlavourRationalParams Params;
Params param;
MultiShiftFunction PowerHalf ;
MultiShiftFunction PowerNegHalf;
MultiShiftFunction PowerQuarter;
MultiShiftFunction PowerNegQuarter;
private:
FermionOperator<Impl> & NumOp;// the basic operator
FermionOperator<Impl> & DenOp;// the basic operator
FermionField PhiEven; // the pseudo fermion field for this trajectory
FermionField PhiOdd; // the pseudo fermion field for this trajectory
public:
OneFlavourEvenOddRatioRationalPseudoFermionAction(FermionOperator<Impl> &_NumOp,
FermionOperator<Impl> &_DenOp,
Params & p
) :
NumOp(_NumOp),
DenOp(_DenOp),
PhiOdd (_NumOp.FermionRedBlackGrid()),
PhiEven(_NumOp.FermionRedBlackGrid()),
param(p)
{
AlgRemez remez(param.lo,param.hi,param.precision);
// MdagM^(+- 1/2)
std::cout<<GridLogMessage << "Generating degree "<<param.degree<<" for x^(1/2)"<<std::endl;
remez.generateApprox(param.degree,1,2);
PowerHalf.Init(remez,param.tolerance,false);
PowerNegHalf.Init(remez,param.tolerance,true);
// MdagM^(+- 1/4)
std::cout<<GridLogMessage << "Generating degree "<<param.degree<<" for x^(1/4)"<<std::endl;
remez.generateApprox(param.degree,1,4);
PowerQuarter.Init(remez,param.tolerance,false);
PowerNegQuarter.Init(remez,param.tolerance,true);
};
virtual void refresh(const GaugeField &U, GridParallelRNG& pRNG) {
// S_f = chi^dag* P(V^dag*V)/Q(V^dag*V)* N(M^dag*M)/D(M^dag*M)* P(V^dag*V)/Q(V^dag*V)* chi
//
// P(phi) = e^{- phi^dag (VdagV)^1/4 (MdagM)^-1/2 (VdagV)^1/4 phi}
// = e^{- phi^dag (VdagV)^1/4 (MdagM)^-1/4 (MdagM)^-1/4 (VdagV)^1/4 phi}
//
// Phi = (VdagV)^-1/4 Mdag^{1/4} eta
//
// P(eta) = e^{- eta^dag eta}
//
// e^{x^2/2 sig^2} => sig^2 = 0.5.
//
// So eta should be of width sig = 1/sqrt(2).
RealD scale = std::sqrt(0.5);
FermionField eta(NumOp.FermionGrid());
FermionField etaOdd (NumOp.FermionRedBlackGrid());
FermionField etaEven(NumOp.FermionRedBlackGrid());
FermionField tmp(NumOp.FermionRedBlackGrid());
gaussian(pRNG,eta); eta=eta*scale;
pickCheckerboard(Even,etaEven,eta);
pickCheckerboard(Odd,etaOdd,eta);
NumOp.ImportGauge(U);
DenOp.ImportGauge(U);
// MdagM^1/4 eta
SchurDifferentiableOperator<Impl> MdagM(DenOp);
ConjugateGradientMultiShift<FermionField> msCG_M(param.MaxIter,PowerQuarter);
msCG_M(MdagM,etaOdd,tmp);
// VdagV^-1/4 MdagM^1/4 eta
SchurDifferentiableOperator<Impl> VdagV(NumOp);
ConjugateGradientMultiShift<FermionField> msCG_V(param.MaxIter,PowerNegQuarter);
msCG_V(VdagV,tmp,PhiOdd);
assert(NumOp.ConstEE() == 1);
assert(DenOp.ConstEE() == 1);
PhiEven = zero;
};
//////////////////////////////////////////////////////
// S_f = chi^dag* P(V^dag*V)/Q(V^dag*V)* N(M^dag*M)/D(M^dag*M)* P(V^dag*V)/Q(V^dag*V)* chi
//////////////////////////////////////////////////////
virtual RealD S(const GaugeField &U) {
NumOp.ImportGauge(U);
DenOp.ImportGauge(U);
FermionField X(NumOp.FermionRedBlackGrid());
FermionField Y(NumOp.FermionRedBlackGrid());
// VdagV^1/4 Phi
SchurDifferentiableOperator<Impl> VdagV(NumOp);
ConjugateGradientMultiShift<FermionField> msCG_V(param.MaxIter,PowerQuarter);
msCG_V(VdagV,PhiOdd,X);
// MdagM^-1/4 VdagV^1/4 Phi
SchurDifferentiableOperator<Impl> MdagM(DenOp);
ConjugateGradientMultiShift<FermionField> msCG_M(param.MaxIter,PowerNegQuarter);
msCG_M(MdagM,X,Y);
// Phidag VdagV^1/4 MdagM^-1/4 MdagM^-1/4 VdagV^1/4 Phi
RealD action = norm2(Y);
return action;
};
// S_f = chi^dag* P(V^dag*V)/Q(V^dag*V)* N(M^dag*M)/D(M^dag*M)* P(V^dag*V)/Q(V^dag*V)* chi
//
// Here, M is some 5D operator and V is the Pauli-Villars field
// N and D makeup the rat. poly of the M term and P and & makeup the rat.poly of the denom term
//
// Need
// dS_f/dU = chi^dag d[P/Q] N/D P/Q chi
// + chi^dag P/Q d[N/D] P/Q chi
// + chi^dag P/Q N/D d[P/Q] chi
//
// P/Q is expressed as partial fraction expansion:
//
// a0 + \sum_k ak/(V^dagV + bk)
//
// d[P/Q] is then
//
// \sum_k -ak [V^dagV+bk]^{-1} [ dV^dag V + V^dag dV ] [V^dag V + bk]^{-1}
//
// and similar for N/D.
//
// Need
// MpvPhi_k = [Vdag V + bk]^{-1} chi
// MpvPhi = {a0 + \sum_k ak [Vdag V + bk]^{-1} }chi
//
// MfMpvPhi_k = [MdagM+bk]^{-1} MpvPhi
// MfMpvPhi = {a0 + \sum_k ak [Mdag M + bk]^{-1} } MpvPhi
//
// MpvMfMpvPhi_k = [Vdag V + bk]^{-1} MfMpvchi
//
virtual void deriv(const GaugeField &U,GaugeField & dSdU) {
const int n_f = PowerNegHalf.poles.size();
const int n_pv = PowerQuarter.poles.size();
std::vector<FermionField> MpvPhi_k (n_pv,NumOp.FermionRedBlackGrid());
std::vector<FermionField> MpvMfMpvPhi_k(n_pv,NumOp.FermionRedBlackGrid());
std::vector<FermionField> MfMpvPhi_k (n_f ,NumOp.FermionRedBlackGrid());
FermionField MpvPhi(NumOp.FermionRedBlackGrid());
FermionField MfMpvPhi(NumOp.FermionRedBlackGrid());
FermionField MpvMfMpvPhi(NumOp.FermionRedBlackGrid());
FermionField Y(NumOp.FermionRedBlackGrid());
GaugeField tmp(NumOp.GaugeGrid());
NumOp.ImportGauge(U);
DenOp.ImportGauge(U);
SchurDifferentiableOperator<Impl> VdagV(NumOp);
SchurDifferentiableOperator<Impl> MdagM(DenOp);
ConjugateGradientMultiShift<FermionField> msCG_V(param.MaxIter,PowerQuarter);
ConjugateGradientMultiShift<FermionField> msCG_M(param.MaxIter,PowerNegHalf);
msCG_V(VdagV,PhiOdd,MpvPhi_k,MpvPhi);
msCG_M(MdagM,MpvPhi,MfMpvPhi_k,MfMpvPhi);
msCG_V(VdagV,MfMpvPhi,MpvMfMpvPhi_k,MpvMfMpvPhi);
RealD ak;
dSdU = zero;
// With these building blocks
//
// dS/dU =
// \sum_k -ak MfMpvPhi_k^dag [ dM^dag M + M^dag dM ] MfMpvPhi_k (1)
// + \sum_k -ak MpvMfMpvPhi_k^\dag [ dV^dag V + V^dag dV ] MpvPhi_k (2)
// -ak MpvPhi_k^dag [ dV^dag V + V^dag dV ] MpvMfMpvPhi_k (3)
//(1)
for(int k=0;k<n_f;k++){
ak = PowerNegHalf.residues[k];
MdagM.Mpc(MfMpvPhi_k[k],Y);
MdagM.MpcDagDeriv(tmp , MfMpvPhi_k[k], Y ); dSdU=dSdU+ak*tmp;
MdagM.MpcDeriv(tmp , Y, MfMpvPhi_k[k] ); dSdU=dSdU+ak*tmp;
}
//(2)
//(3)
for(int k=0;k<n_pv;k++){
ak = PowerQuarter.residues[k];
VdagV.Mpc(MpvPhi_k[k],Y);
VdagV.MpcDagDeriv(tmp,MpvMfMpvPhi_k[k],Y); dSdU=dSdU+ak*tmp;
VdagV.MpcDeriv (tmp,Y,MpvMfMpvPhi_k[k]); dSdU=dSdU+ak*tmp;
VdagV.Mpc(MpvMfMpvPhi_k[k],Y); // V as we take Ydag
VdagV.MpcDeriv (tmp,Y, MpvPhi_k[k]); dSdU=dSdU+ak*tmp;
VdagV.MpcDagDeriv(tmp,MpvPhi_k[k], Y); dSdU=dSdU+ak*tmp;
}
//dSdU = Ta(dSdU);
};
};
}
}
#endif
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