squiggle.c

Self-contained Monte Carlo estimation in C99
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example.c (1124B)

      1 #include "../../../squiggle.h"
      2 #include <stdio.h>
      3 #include <stdlib.h>
      4 
      5 double sample_0(uint64_t* seed) { UNUSED(seed); return 0; }
      6 double sample_1(uint64_t* seed) { UNUSED(seed); return 1; }
      7 double sample_few(uint64_t* seed) { return sample_to(1, 3, seed); }
      8 double sample_many(uint64_t* seed) { return sample_to(2, 10, seed); }
      9 
     10 double sample_model(uint64_t* seed){
     11 
     12     double p_a = 0.8;
     13     double p_b = 0.5;
     14     double p_c = p_a * p_b;
     15 
     16     int n_dists = 4;
     17     double weights[] = { 1 - p_c, p_c / 2, p_c / 4, p_c / 4 };
     18     double (*samplers[])(uint64_t*) = { sample_0, sample_1, sample_few, sample_many };
     19     double result = sample_mixture(samplers, weights, n_dists, seed);
     20 
     21     return result;
     22 }
     23 
     24 int main()
     25 {
     26     // set randomness seed
     27     uint64_t* seed = malloc(sizeof(uint64_t));
     28     *seed = 1000; // xorshift can't start with 0
     29 
     30     int n_samples = 1000000;
     31     double* result_many = (double*)malloc((size_t)n_samples * sizeof(double));
     32     for (int i = 0; i < n_samples; i++) {
     33         result_many[i] = sample_model(seed);
     34     }
     35     printf("Mean: %f\n", array_mean(result_many, n_samples));
     36 
     37     free(seed);
     38 }