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test/triqs/mc_tools directory added, with an example of simple random walker

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Laura Messio 2013-07-30 21:46:03 +02:00 committed by Olivier Parcollet
parent a5b122d91a
commit 6239dee8b3
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different_moves.ipynb Normal file
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test/triqs/mc_tools/CMakeLists.txt Normal file
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link_libraries (triqs)
all_tests()

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test/triqs/mc_tools/different_moves_mc.cpp Normal file
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// The goal of this program is to give an example of the use of the probability for proposing a move (here, pl and pr)
// The walker try to go towards its left with probability 2*pl/(pl+pr) (pl is given to the move_left constructor),
// or towards the right with probability 2*pr/(pl+pr) (pr is given to the move_right constructor).
// The left move is accepted with probability proba=pr/pl and the right move with probability proba=pl/pr (in reality, each time with probability min(1,proba) ).
// A python notebook is associated to this example, with the comparison to the theoretical gaussian histogram.
#define TRIQS_ARRAYS_ENFORCE_BOUNDCHECK
#include <triqs/utility/callbacks.hpp>
#include <triqs/mc_tools/mc_generic.hpp>
triqs::arrays::array<std::complex<double>,1> make_array( std::complex<double> c){return {c}; };
struct configuration {
int x; //position of the walker
configuration():x(0){} //constructor
};
//------------------------------------------------------------
// MOVES
//------------------------------------------------------------
struct move_left {
configuration *config;
double proba;
triqs::mc_tools::random_generator &RND;
move_left(configuration &config_, double pl, double pr, triqs::mc_tools::random_generator &RND_):config(&config_), proba(pr/pl), RND(RND_){} //constructor
double attempt() {return proba; }
double accept() {config->x += -1; return 1; }
void reject() {}
};
struct move_right {
configuration *config;
double proba;
triqs::mc_tools::random_generator &RND;
move_right( configuration &config_, double pl, double pr, triqs::mc_tools::random_generator &RND_):config(&config_), proba(pl/pr), RND(RND_){} //constructor
double attempt() {return proba; }
double accept() {config->x += 1; return 1; }
void reject() {}
};
//------------------------------------------------------------
// MEASUREMENTS
//------------------------------------------------------------
struct compute_histo{
configuration *config;
triqs::arrays::array<double,1> H; // an histogram
int tot, xmax;
compute_histo(configuration &config_, triqs::arrays::array<double,1> &H_, int xmax_) : config(&config_), H(H_), xmax(xmax_), tot(0) {}
void accumulate(double sign) {
if( config->x+xmax>=0 && config->x-xmax<0){
H( floor( (config->x+xmax) ) ) += 1;
tot += 1;
}
config->x=0;
}
void collect_results(boost::mpi::communicator const &c) {
H/=tot;
H5::H5File file("histo.h5",H5F_ACC_TRUNC);
h5_write(file,"H",H);
}
};
//------------------------------------------------------------
// MAIN
//------------------------------------------------------------
int main(int argc, char* argv[]) {
// initialize mpi
boost::mpi::environment env(argc, argv);
boost::mpi::communicator world;
// greeting
if (world.rank() == 0) std::cout << "Random walk calculation" << std::endl;
// prepare the MC parameters
int N_Cycles = 100000;
int Length_Cycle = 100;
int N_Warmup_Cycles = 0;
std::string Random_Name = "";
int Random_Seed = 374982 + world.rank() * 273894;
int Verbosity = (world.rank() == 0 ? 3 : 0);
int xmax=floor(4*sqrt(Length_Cycle) ); //max of the position registered in the histogram
double pl=1.5, pr=1; //non normalized probabilities for proposing a left or right move
H5::H5File file("params.h5",H5F_ACC_TRUNC);
h5_write(file,"pr",make_array(pr));
h5_write(file,"pl",make_array(pl));
h5_write(file,"xmax",make_array(xmax));
h5_write(file,"N_Cycles",make_array(N_Cycles));
h5_write(file,"Length_Cycle",make_array(Length_Cycle));
// construct a Monte Carlo loop
triqs::mc_tools::mc_generic<double> IntMC(N_Cycles, Length_Cycle, N_Warmup_Cycles, Random_Name, Random_Seed, Verbosity);
// construct configuration
configuration config;
triqs::arrays::array<double,1> H(2*xmax);
H()=0;
// add moves and measures
IntMC.add_move(move_left (config, pl, pr, IntMC.rng() ), "left move", pl);
IntMC.add_move(move_right(config, pl, pr, IntMC.rng() ), "right move", pr);
IntMC.add_measure(compute_histo(config, H, xmax), "histogramn measure");
// Run and collect results
IntMC.start(1.0, triqs::utility::clock_callback(600));
IntMC.collect_results(world);
return 0;
}