贝叶斯算法实例（c语言）

#include <stdlib.h> int main(int argc, char *argv[]) { double sum_w1, sum_w2; int i, num_samples; num_samples = atoi(argv[1]); /* Seed the random-number generator with current time so that * the numbers will be different every time we run. */ srand( (unsigned)time( NULL ) ); /* Likelihood weighting part. */ sum_w1 = sum_w2 = 0; for (i=0; i<num_samples; i++) { double weight; int a, b; weight = 1.0; a = coin_toss(0.2); b = (a==0)?coin_toss(0.6):coin_toss(0.7); if (b==0) weight *= 0.4; else weight *= 0.1; if (a==1) sum_w1 += weight; sum_w2 += weight; } /* Display result. */ printf("Prob(A|B)=%g\n", sum_w1/sum_w2); } /* Returns 1 with probability p. If it doesn't return 1, returns 0. */ int coin_toss(double p) { double t = (double)rand() / RAND_MAX; return (t>p)?0:1; }