mirror of
https://github.com/paboyle/Grid.git
synced 2024-09-20 17:25:37 +01:00
134 lines
3.6 KiB
C++
134 lines
3.6 KiB
C++
//--------------------------------------------------------------------
|
|
/*! @file HMC.h
|
|
* @brief Classes for Hybrid Monte Carlo update
|
|
*
|
|
* @author Guido Cossu
|
|
* Time-stamp: <2015-07-30 16:58:26 neo>
|
|
*/
|
|
//--------------------------------------------------------------------
|
|
#ifndef HMC_INCLUDED
|
|
#define HMC_INCLUDED
|
|
|
|
#include <string>
|
|
|
|
|
|
namespace Grid{
|
|
namespace QCD{
|
|
|
|
|
|
struct HMCparameters{
|
|
Integer Nsweeps; /* @brief Number of sweeps in this run */
|
|
Integer TotalSweeps; /* @brief If provided, the total number of sweeps */
|
|
Integer ThermalizationSteps;
|
|
Integer StartingConfig;
|
|
Integer SaveInterval; //Setting to 0 does not save configurations
|
|
std::string Filename_prefix; // To save configurations and rng seed
|
|
|
|
HMCparameters();
|
|
};
|
|
|
|
// template <class GaugeField, class Integrator, class Smearer, class Boundary>
|
|
template <class GaugeField, class IntegratorType>
|
|
class HybridMonteCarlo {
|
|
private:
|
|
|
|
const HMCparameters Params;
|
|
|
|
GridSerialRNG &sRNG; // Fixme: need a RNG management strategy.
|
|
GridParallelRNG &pRNG; // Fixme: need a RNG management strategy.
|
|
|
|
IntegratorType &TheIntegrator;
|
|
|
|
/////////////////////////////////////////////////////////
|
|
// Metropolis step
|
|
/////////////////////////////////////////////////////////
|
|
bool metropolis_test(const RealD DeltaH){
|
|
|
|
RealD rn_test;
|
|
|
|
RealD prob = std::exp(-DeltaH);
|
|
|
|
random(sRNG,rn_test);
|
|
|
|
std::cout<<GridLogMessage<< "--------------------------------------------\n";
|
|
std::cout<<GridLogMessage<< "dH = "<<DeltaH << " Random = "<< rn_test <<"\n";
|
|
std::cout<<GridLogMessage<< "Acc. Probability = " << ((prob<1.0)? prob: 1.0)<< " ";
|
|
|
|
if((prob >1.0) || (rn_test <= prob)){ // accepted
|
|
std::cout<<GridLogMessage <<"-- ACCEPTED\n";
|
|
return true;
|
|
} else { // rejected
|
|
std::cout<<GridLogMessage <<"-- REJECTED\n";
|
|
return false;
|
|
}
|
|
|
|
}
|
|
|
|
/////////////////////////////////////////////////////////
|
|
// Evolution
|
|
/////////////////////////////////////////////////////////
|
|
RealD evolve_step(GaugeField& U){
|
|
|
|
TheIntegrator.refresh(U,pRNG); // set U and initialize P and phi's
|
|
|
|
RealD H0 = TheIntegrator.S(U); // initial state action
|
|
|
|
std::cout<<GridLogMessage<<"Total H before = "<< H0 << "\n";
|
|
|
|
TheIntegrator.integrate(U);
|
|
|
|
RealD H1 = TheIntegrator.S(U); // updated state action
|
|
|
|
std::cout<<GridLogMessage<<"Total H after = "<< H1 << "\n";
|
|
|
|
return (H1-H0);
|
|
}
|
|
|
|
public:
|
|
|
|
/////////////////////////////////////////
|
|
// Constructor
|
|
/////////////////////////////////////////
|
|
HybridMonteCarlo(HMCparameters Pms, IntegratorType &_Int, GridSerialRNG &_sRNG, GridParallelRNG &_pRNG ) :
|
|
Params(Pms),
|
|
TheIntegrator(_Int),
|
|
sRNG(_sRNG),
|
|
pRNG(_pRNG)
|
|
{
|
|
}
|
|
~HybridMonteCarlo(){};
|
|
|
|
|
|
void evolve(GaugeField& Uin){
|
|
|
|
Real DeltaH;
|
|
|
|
// Thermalizations
|
|
for(int iter=1; iter <= Params.ThermalizationSteps; ++iter){
|
|
std::cout<<GridLogMessage << "-- # Thermalization step = "<< iter << "\n";
|
|
|
|
DeltaH = evolve_step(Uin);
|
|
std::cout<<GridLogMessage<< "dH = "<< DeltaH << "\n";
|
|
}
|
|
|
|
// Actual updates (evolve a copy Ucopy then copy back eventually)
|
|
GaugeField Ucopy(Uin._grid);
|
|
for(int iter=Params.StartingConfig; iter < Params.Nsweeps+Params.StartingConfig; ++iter){
|
|
std::cout<<GridLogMessage << "-- # Sweep = "<< iter << "\n";
|
|
|
|
Ucopy = Uin;
|
|
|
|
DeltaH = evolve_step(Ucopy);
|
|
|
|
if(metropolis_test(DeltaH)) Uin = Ucopy;
|
|
|
|
}
|
|
}
|
|
};
|
|
|
|
}// QCD
|
|
}// Grid
|
|
|
|
|
|
#endif
|