testRandom.c 3.99 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51
/*******************************************************************************
 * This file is part of SWIFT.
 * Copyright (C) 2019 Matthieu Schaller (schaller@strw.leidenuniv.nl)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 ******************************************************************************/

/* Config parameters. */
#include "../config.h"

#include <fenv.h>

/* Local headers. */
#include "swift.h"

int main(int argc, char* argv[]) {

  /* Initialize CPU frequency, this also starts time. */
  unsigned long long cpufreq = 0;
  clocks_set_cpufreq(cpufreq);

/* Choke on FPEs */
#ifdef HAVE_FE_ENABLE_EXCEPT
  feenableexcept(FE_DIVBYZERO | FE_INVALID | FE_OVERFLOW);
#endif

  /* Get some randomness going */
  const int seed = time(NULL);
  message("Seed = %d", seed);
  srand(seed);

  /* Time-step size */
  const int time_bin = 29;

  /* Try a few different values for the ID */
  for (int i = 0; i < 20; ++i) {

    const long long id = rand() * (1LL << 31) + rand();
    const integertime_t increment = (1LL << time_bin);
52
    const long long idoffset = id + 2;
53 54 55 56 57 58

    message("Testing id=%lld time_bin=%d", id, time_bin);

    double total = 0., total2 = 0.;
    int count = 0;

59
    /* Pearson correlation variables for different times */
60 61
    double sum_previous_current = 0.;
    double previous = 0.;
62 63 64 65 66

    /* Pearson correlation for two different IDs */
    double pearsonIDs = 0.;
    double totalID = 0.;
    double total2ID = 0.;
67

68 69 70 71 72 73 74 75 76 77
    /* Check that the numbers are uniform over the full-range of useful
     * time-steps */
    for (integertime_t ti_current = 0LL; ti_current < max_nr_timesteps;
         ti_current += increment) {

      ti_current += increment;

      const double r =
          random_unit_interval(id, ti_current, random_number_star_formation);

78 79 80
      const double r_2ndid =
          random_unit_interval(idoffset, ti_current, random_number_star_formation);

81 82 83
      total += r;
      total2 += r * r;
      count++;
84

85
      /* For the pearson correlation of time i and i-1 */
86 87
      sum_previous_current += r * previous;
      previous = r;
88 89 90 91 92

      /* Pearson correlation for small different IDs */
      pearsonIDs += r * r_2ndid;
      totalID += r_2ndid;
      total2ID += r_2ndid * r_2ndid;
93 94 95 96 97
    }

    const double mean = total / (double)count;
    const double var = total2 / (double)count - mean * mean;

98 99 100 101 102 103 104 105 106 107 108
    /* Pearson correlation calculation for different times */
    const double mean_xy = sum_previous_current / ( (double)count -1.f);
    const double correlation = (mean_xy-mean*mean)/var;
    
    /* Pearson correlation for different IDs */
    const double meanID = totalID / (double)count;
    const double varID = total2ID / (double)count - meanID * meanID;

    const double meanID_xy = pearsonIDs / (double)count;
    const double correlationID = (meanID_xy - mean*meanID) / pow(var * varID, .5f);

109 110
    /* Verify that the mean and variance match the expected values for a uniform
     * distribution */
111 112
    if ((fabs(mean - 0.5) / 0.5 > 2e-4) ||
        (fabs(var - 1. / 12.) / (1. / 12.) > 1e-3) ||
113 114
        (fabs(correlation) > 3e-4) ||
        (fabs(correlationID) > 3e-4) ) {
115
      message("Test failed!");
116 117
      message("Result:    count=%d mean=%f var=%f, correlation=%f ID correlation=%f", count, mean, var, correlation, correlationID);
      message("Expected:  count=%d mean=%f var=%f, correlation=%f ID correlation=%f", count, 0.5f, 1. / 12., 0., 0.);
118 119 120 121 122 123
      return 1;
    }
  }

  return 0;
}