free_energy.cpp


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#include <iomanip>
#include <iostream>

#include "aztec.hpp"

int main(int argc, char* argv[]) {
  unsigned n = 100;
  unsigned m = 100;
  Real T0 = 1;
  Real T1 = 10;
  Real ΔT = 1;

  int opt;

  while ((opt = getopt(argc, argv, "n:m:0:1:d:")) != -1) {
    switch (opt) {
    case 'n':
      n = atoi(optarg);
      break;
    case 'm':
      m = (unsigned)atof(optarg);
      break;
    case '0':
      T0 = atof(optarg);
      break;
    case '1':
      T1 = atof(optarg);
      break;
    case 'd':
      ΔT = atof(optarg);
      break;
    default:
      exit(1);
    }
  }

  Rng r;
  AztecDiamond a(n);
  a.setWeights(r);

  for (Real T = T0; T <= T1; T += ΔT) {
    Real avgFreeEnergy = 0;

    for (unsigned i = 0; i < m; i++) {
      a.computeWeights(T);
      avgFreeEnergy += a.computeProbabilities();
    }

    std::cout << std::setprecision(20) << T << " " << -T * avgFreeEnergy / m / a.vertices.size()
              << std::endl;
  }

  return 0;
}