C语言：实现一个生成正态随机数的函数，对应的算法是Marsaglia-Bray 算法，重复题目一的相 关过程，即生成一定数量（1000）个随机数（正态分布），然后用图表示它的分布。

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define N 1000

double randn() {
    static double u, v, s;
    static int phase = 0;
    double z;

    if (phase == 0) {
        do {
            u = (double)rand() / RAND_MAX * 2.0 - 1.0;
            v = (double)rand() / RAND_MAX * 2.0 - 1.0;
            s = u * u + v * v;
        } while (s >= 1.0 || s == 0.0);
        z = u * sqrt(-2.0 * log(s) / s);
    } else {
        z = v * sqrt(-2.0 * log(s) / s);
    }
    phase = 1 - phase;
    return z;
}

int main() {
    int i;
    double a[N], sum = 0.0, mean, std_dev;

    srand(time(NULL));
    for (i = 0; i < N; i++) {
        a[i] = randn();
        sum += a[i];
    }
    mean = sum / N;

    sum = 0.0;
    for (i = 0; i < N; i++) {
        sum += pow(a[i] - mean, 2);
    }
    std_dev = sqrt(sum / N);

    printf("mean = %f, std_dev = %f\n", mean, std_dev);

    FILE *fp = fopen("output.txt", "w");
    for (i = 0; i < N; i++) {
        fprintf(fp, "%f\n", a[i]);
    }
    fclose(fp);

    return 0;
}

使用Matplotlib绘制正态分布的图像：

import numpy as np
import matplotlib.pyplot as plt

data = np.genfromtxt('output.txt')
plt.hist(data, bins=50, density=True)
plt.show()

得到的图像：