Grid/lib/qcd/observables/topological_charge.h

/*************************************************************************************

Grid physics library, www.github.com/paboyle/Grid

Source file: ./lib/qcd/modules/topological_charge.h

Copyright (C) 2017

Author: Guido Cossu <guido.cossu@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 HMC_TOP_CHARGE_H
#define HMC_TOP_CHARGE_H

NAMESPACE_BEGIN(Grid);

struct TopologySmearingParameters : Serializable {
  GRID_SERIALIZABLE_CLASS_MEMBERS(TopologySmearingParameters,
				  int, steps,
				  float, step_size,
				  int, meas_interval,
				  float, maxTau);

  TopologySmearingParameters(int s = 0, float ss = 0.0f, int mi = 0, float mT = 0.0f):
    steps(s), step_size(ss), meas_interval(mi), maxTau(mT){}

  template < class ReaderClass >
  TopologySmearingParameters(Reader<ReaderClass>& Reader){
    read(Reader, "Smearing", *this);  
  }  
};



struct TopologyObsParameters : Serializable {
  GRID_SERIALIZABLE_CLASS_MEMBERS(TopologyObsParameters,
				  int, interval,
				  bool, do_smearing,
				  TopologySmearingParameters, Smearing);  

  TopologyObsParameters(int interval = 1, bool smearing = false):
    interval(interval), Smearing(smearing){}

  template <class ReaderClass >
  TopologyObsParameters(Reader<ReaderClass>& Reader){
    read(Reader, "TopologyMeasurement", *this);
  }
};


// this is only defined for a gauge theory
template <class Impl>
class TopologicalCharge : public HmcObservable<typename Impl::Field> {
  TopologyObsParameters Pars;

public:
  // here forces the Impl to be of gauge fields
  // if not the compiler will complain
  INHERIT_GIMPL_TYPES(Impl);

  // necessary for HmcObservable compatibility
  typedef typename Impl::Field Field;

  TopologicalCharge(int interval = 1, bool do_smearing = false):
    Pars(interval, do_smearing){}
    
  TopologicalCharge(TopologyObsParameters P):Pars(P){
    std::cout << GridLogDebug << "Creating TopologicalCharge " << std::endl;
  }

  void TrajectoryComplete(int traj,
			  Field &U,
			  GridSerialRNG &sRNG,
			  GridParallelRNG &pRNG) {

    if (traj%Pars.interval == 0){
      // Smearing
      Field Usmear = U;
      int def_prec = std::cout.precision();
        
      if (Pars.do_smearing){
	// using wilson flow by default here
	WilsonFlow<PeriodicGimplR> WF(Pars.Smearing.steps, Pars.Smearing.step_size, Pars.Smearing.meas_interval);
	WF.smear_adaptive(Usmear, U, Pars.Smearing.maxTau);
	Real T0   = WF.energyDensityPlaquette(Usmear);
	std::cout << GridLogMessage << std::setprecision(std::numeric_limits<Real>::digits10 + 1)
		  << "T0                : [ " << traj << " ] "<< T0 << std::endl;
      }

      Real q    = WilsonLoops<Impl>::TopologicalCharge(Usmear);
      std::cout << GridLogMessage
		<< std::setprecision(std::numeric_limits<Real>::digits10 + 1)
		<< "Topological Charge: [ " << traj << " ] "<< q << std::endl;

      std::cout.precision(def_prec);
    }
  }

};

NAMESPACE_END(Grid);

#endif  //  HMC_TOP_CHARGE_H