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https://github.com/triqs/dft_tools
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put back literalinclude instead of triqs_example for c++
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tayral
parent
880f30b086
commit
a9e5f20c39
@ -6,4 +6,7 @@ A lazy sum
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Here is a little functional `sum` that sums a function f over various domains
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and accepts lazy expressions as arguments.
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.. triqs_example:: src/sum_functional.cpp
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.. literalinclude:: src/sum_functional.cpp
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The output is:
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.. literalinclude:: src/sum_functional.output
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@ -3,6 +3,9 @@
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Full example: Monte-Carlo simulation of the 2D Ising model
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===========================================================
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.. literalinclude:: src/ising2d.cpp
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.. triqs_example:: ising2d_0.cpp
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The output is:
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.. literalinclude:: src/ising2d.output
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@ -1,181 +0,0 @@
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#include <triqs/mc_tools/random_generator.hpp>
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#include <triqs/mc_tools/mc_generic.hpp>
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#include <triqs/utility/callbacks.hpp>
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#include <triqs/arrays.hpp>
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#include <triqs/statistics.hpp>
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#include <vector>
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#include <iostream>
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#include <fstream>
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//#define TRIQS_ARRAYS_ENFORCE_BOUNDCHECK
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// H = -J \sum_<ij> s_i s_j - h \sum_i s_i
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// theoretical T_c = 2/log(1+sqrt(2)) for J = 1.0
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using namespace triqs::statistics;
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/**************
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* config
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**************/
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struct configuration {
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// N is the linear size of spin matrix, M the total magnetization,
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// beta the inverse temperature, J the coupling,
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// field the magnetic field and energy the energy of the configuration
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int N, M;
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double beta, J, field, energy;
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// the chain of spins: true means "up", false means "down"
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triqs::arrays::array<bool,2> chain;
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observable<double> M_stack;
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// constructor
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configuration(int N_, double beta_, double J_, double field_):
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N(N_), M(-N*N), beta(beta_), J(J_), field(field_), energy(-J*4*N/2+N*field), chain(N,N) , M_stack(){
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chain()=false;
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}
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};
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/**************
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* move
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**************/
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// A move flipping a random spin
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struct flip {
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configuration * config;
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triqs::mc_tools::random_generator &RNG;
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struct site { int i,j ;};//small struct storing indices of a given site
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site s;
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double delta_energy;
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// constructor
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flip(configuration & config_, triqs::mc_tools::random_generator & RNG_) :
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config(&config_), RNG(RNG_) {}
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// find the neighbours with periodicity
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std::vector<site> neighbors(site s, int N){
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std::vector<site> nns(4);
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int counter=0;
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for(int i=-1;i<=1;i++){
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for(int j=-1;j<=1;j++){
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if ((i==0) != (j==0)) //xor
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nns[counter++] = site{(s.i+i)%N, (s.j+j)%N};
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}
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}
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return nns;
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}
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double attempt() {
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// pick a random site
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int index = RNG(config->N*config->N);
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s = {index%config->N, index/config->N};
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// compute energy difference from field
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delta_energy = (config->chain(s.i,s.j) ? 2 : -2) * config->field;
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auto nns = neighbors(s,config->N); //nearest-neighbors
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double sum_neighbors=0.0;
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for(auto & x:nns) sum_neighbors += ((config->chain(x.i,x.j))?1:-1);
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// compute energy difference from J
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delta_energy += - sum_neighbors * config->J* (config->chain(s.i,s.j)?-2:2);
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// return Metroplis ratio
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return std::exp(-config->beta * delta_energy);
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}
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// if move accepted just flip site and update energy and magnetization
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double accept() {
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config->M += (config->chain(s.i,s.j) ? -2 : 2);
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config->chain(s.i,s.j) = !config->chain(s.i,s.j);
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config->energy += delta_energy;
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return 1.0;
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}
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// nothing to do if the move is rejected
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void reject() {}
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};
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/**************
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* measure
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**************/
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struct compute_m {
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configuration * config;
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double Z, M;
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compute_m(configuration & config_) : config(&config_), Z(0), M(0) {}
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// accumulate Z and magnetization
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void accumulate(int sign) {
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Z += sign;
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M += config->M;
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//config->M_stack << double(config->M/(config->N*config->N));
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config->M_stack << config->M;
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}
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// get final answer M / (Z*N)
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void collect_results(boost::mpi::communicator const &c) {
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double sum_Z, sum_M;
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boost::mpi::reduce(c, Z, sum_Z, std::plus<double>(), 0);
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boost::mpi::reduce(c, M, sum_M, std::plus<double>(), 0);
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if (c.rank() == 0) {
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std::cout << "@Beta:\t"<<config->beta<<"\tMagnetization:\t" << sum_M / (sum_Z*(config->N*config->N)) << std::endl ;
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std::cout << "average_and_error(M) = " << average_and_error(config->M_stack) << std::endl;
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std::cout << "#Beta:\t"<<config->beta<<"\tAutocorr_time:\t" << autocorrelation_time_from_binning(config->M_stack) << std::endl;
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std::ofstream outfile("magnetization_series.dat");
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for(int i=0;i<config->M_stack.size();i++)
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outfile << config->M_stack[i] <<std::endl;
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outfile.close();
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}
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}
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};
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int main(int argc, char* argv[]) {
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// initialize mpi
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boost::mpi::environment env(argc, argv);
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boost::mpi::communicator world;
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double H=0.0,B=0.5;
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int N=20;
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int nc = 100000;
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if(argc==4){
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H = atof(argv[1]);//field
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B = atof(argv[2]);//inverse temp
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N = atoi(argv[3]);//size along one dimension
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nc = 1000000 ;
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}
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if (world.rank() == 0)
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std::cout << "2D Ising with field = " << H << ", beta = " << B << ", N = " << N << std::endl;
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// Prepare the MC parameters
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int n_cycles = nc;
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int length_cycle = 100;
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int n_warmup_cycles = 100000;
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std::string random_name = "";
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int random_seed = 374982 + world.rank() * 273894;
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int verbosity = (world.rank() == 0 ? 2 : 0);
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// Construct a Monte Carlo loop
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triqs::mc_tools::mc_generic<double> IsingMC(n_cycles, length_cycle, n_warmup_cycles,
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random_name, random_seed, verbosity);
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// parameters of the model
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int length = N;
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double J = 1.0;
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double field = H;
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double beta = B;
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// construct configuration
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configuration config(length, beta, J, field);
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// add moves and measures
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IsingMC.add_move(flip(config, IsingMC.rng()), "spin flip");
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IsingMC.add_measure(compute_m(config), "measure magnetization");
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// Run and collect results
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IsingMC.start(1.0, triqs::utility::clock_callback(-1));
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IsingMC.collect_results(world);
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return 0;
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}
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