生成指数分布的随机数

这是因为您没有声明类型lambda,更正了结果在您寻求的范围内.如果未声明,旧编译器将认为它是int.

#include 
#include 
#include 
#include 

double ran_expo(double lambda){
    double u;
    u = rand() / (RAND_MAX + 1.0);
    return -log(1- u) / lambda;
}

int main(void)
{
    int i;
    srand((unsigned)time(NULL));
    for (i=0; i<20; i++)
        printf("%f\n", ran_expo(0.05));
    return 0;
}

节目输出:

0.025040
16.582459
4.296027
33.079902
17.589123
13.073084
8.624299
45.254803
34.611211
27.454302
3.825699
39.168172
24.790600
14.411160
7.247698
0.301951
1.917010
9.065004
3.187146
3.627885