From 70ab598c96401761996b78f6d0343f16267c6e73 Mon Sep 17 00:00:00 2001
From: Azusa Yamaguchi <ayamaguc@staffmail.ed.ac.uk>
Date: Thu, 8 Jun 2017 22:22:23 +0100
Subject: [PATCH] Move gfix into utils

---
 lib/qcd/utils/GaugeFix.h | 188 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 188 insertions(+)
 create mode 100644 lib/qcd/utils/GaugeFix.h

diff --git a/lib/qcd/utils/GaugeFix.h b/lib/qcd/utils/GaugeFix.h
new file mode 100644
index 00000000..4ff216e4
--- /dev/null
+++ b/lib/qcd/utils/GaugeFix.h
@@ -0,0 +1,188 @@
+    /*************************************************************************************
+
+    grid` physics library, www.github.com/paboyle/Grid 
+
+    Copyright (C) 2015
+
+Author: Azusa Yamaguchi <ayamaguc@staffmail.ed.ac.uk>
+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 */
+//#include <Grid/Grid.h>
+
+using namespace Grid;
+using namespace Grid::QCD;
+
+template <class Gimpl> 
+class FourierAcceleratedGaugeFixer  : public Gimpl {
+  public:
+  INHERIT_GIMPL_TYPES(Gimpl);
+
+  typedef typename Gimpl::GaugeLinkField GaugeMat;
+  typedef typename Gimpl::GaugeField GaugeLorentz;
+
+  static void GaugeLinkToLieAlgebraField(const std::vector<GaugeMat> &U,std::vector<GaugeMat> &A) {
+    for(int mu=0;mu<Nd;mu++){
+      Complex cmi(0.0,-1.0);
+      A[mu] = Ta(U[mu]) * cmi;
+    }
+  }
+  static void DmuAmu(const std::vector<GaugeMat> &A,GaugeMat &dmuAmu) {
+    dmuAmu=zero;
+    for(int mu=0;mu<Nd;mu++){
+      dmuAmu = dmuAmu + A[mu] - Cshift(A[mu],mu,-1);
+    }
+  }  
+  static void SteepestDescentGaugeFix(GaugeLorentz &Umu,Real & alpha,int maxiter,Real Omega_tol, Real Phi_tol,bool Fourier=false) {
+    GridBase *grid = Umu._grid;
+
+    Real org_plaq      =WilsonLoops<Gimpl>::avgPlaquette(Umu);
+    Real org_link_trace=WilsonLoops<Gimpl>::linkTrace(Umu); 
+    Real old_trace = org_link_trace;
+    Real trG;
+
+    std::vector<GaugeMat> U(Nd,grid);
+                 GaugeMat dmuAmu(grid);
+
+    for(int i=0;i<maxiter;i++){
+      for(int mu=0;mu<Nd;mu++) U[mu]= PeekIndex<LorentzIndex>(Umu,mu);
+      if ( Fourier==false ) { 
+	trG = SteepestDescentStep(U,alpha,dmuAmu);
+      } else { 
+	trG = FourierAccelSteepestDescentStep(U,alpha,dmuAmu);
+      }
+      for(int mu=0;mu<Nd;mu++) PokeIndex<LorentzIndex>(Umu,U[mu],mu);
+      // Monitor progress and convergence test 
+      // infrequently to minimise cost overhead
+      if ( i %20 == 0 ) { 
+	Real plaq      =WilsonLoops<Gimpl>::avgPlaquette(Umu);
+	Real link_trace=WilsonLoops<Gimpl>::linkTrace(Umu); 
+
+	if (Fourier) 
+	  std::cout << GridLogMessage << "Fourier Iteration "<<i<< " plaq= "<<plaq<< " dmuAmu " << norm2(dmuAmu)<< std::endl;
+	else 
+	  std::cout << GridLogMessage << " Iteration "<<i<< " plaq= "<<plaq<< " dmuAmu " << norm2(dmuAmu)<< std::endl;
+	
+	Real Phi  = 1.0 - old_trace / link_trace ;
+	Real Omega= 1.0 - trG;
+
+
+	std::cout << GridLogMessage << " Iteration "<<i<< " Phi= "<<Phi<< " Omega= " << Omega<< " trG " << trG <<std::endl;
+	if ( (Omega < Omega_tol) && ( ::fabs(Phi) < Phi_tol) ) {
+	  std::cout << GridLogMessage << "Converged ! "<<std::endl;
+	  return;
+	}
+
+	old_trace = link_trace;
+
+      }
+    }
+  };
+  static Real SteepestDescentStep(std::vector<GaugeMat> &U,Real & alpha, GaugeMat & dmuAmu) {
+    GridBase *grid = U[0]._grid;
+
+    std::vector<GaugeMat> A(Nd,grid);
+    GaugeMat g(grid);
+
+    GaugeLinkToLieAlgebraField(U,A);
+    ExpiAlphaDmuAmu(A,g,alpha,dmuAmu);
+
+
+    Real vol = grid->gSites();
+    Real trG = TensorRemove(sum(trace(g))).real()/vol/Nc;
+
+    SU<Nc>::GaugeTransform(U,g);
+
+    return trG;
+  }
+
+  static Real FourierAccelSteepestDescentStep(std::vector<GaugeMat> &U,Real & alpha, GaugeMat & dmuAmu) {
+
+    GridBase *grid = U[0]._grid;
+
+    Real vol = grid->gSites();
+
+    FFT theFFT((GridCartesian *)grid);
+
+    LatticeComplex  Fp(grid);
+    LatticeComplex  psq(grid); psq=zero;
+    LatticeComplex  pmu(grid); 
+    LatticeComplex   one(grid); one = Complex(1.0,0.0);
+
+    GaugeMat g(grid);
+    GaugeMat dmuAmu_p(grid);
+    std::vector<GaugeMat> A(Nd,grid);
+
+    GaugeLinkToLieAlgebraField(U,A);
+
+    DmuAmu(A,dmuAmu);
+
+    theFFT.FFT_all_dim(dmuAmu_p,dmuAmu,FFT::forward);
+
+    //////////////////////////////////
+    // Work out Fp = psq_max/ psq...
+    //////////////////////////////////
+    std::vector<int> latt_size = grid->GlobalDimensions();
+    std::vector<int> coor(grid->_ndimension,0);
+    for(int mu=0;mu<Nd;mu++) {
+
+      Real TwoPiL =  M_PI * 2.0/ latt_size[mu];
+      LatticeCoordinate(pmu,mu);
+      pmu = TwoPiL * pmu ;
+      psq = psq + 4.0*sin(pmu*0.5)*sin(pmu*0.5); 
+    }
+
+    Complex psqMax(16.0);
+    Fp =  psqMax*one/psq;
+
+    /*
+    static int once;
+    if ( once == 0 ) { 
+      std::cout << " Fp " << Fp <<std::endl;
+      once ++;
+      }*/
+
+    pokeSite(TComplex(1.0),Fp,coor);
+
+    dmuAmu_p  = dmuAmu_p * Fp; 
+
+    theFFT.FFT_all_dim(dmuAmu,dmuAmu_p,FFT::backward);
+
+    GaugeMat ciadmam(grid);
+    Complex cialpha(0.0,-alpha);
+    ciadmam = dmuAmu*cialpha;
+    SU<Nc>::taExp(ciadmam,g);
+
+    Real trG = TensorRemove(sum(trace(g))).real()/vol/Nc;
+
+    SU<Nc>::GaugeTransform(U,g);
+
+    return trG;
+  }
+
+  static void ExpiAlphaDmuAmu(const std::vector<GaugeMat> &A,GaugeMat &g,Real & alpha, GaugeMat &dmuAmu) {
+    GridBase *grid = g._grid;
+    Complex cialpha(0.0,-alpha);
+    GaugeMat ciadmam(grid);
+    DmuAmu(A,dmuAmu);
+    ciadmam = dmuAmu*cialpha;
+    SU<Nc>::taExp(ciadmam,g);
+  }  
+};
+