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