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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <math.h>
  4. #include <time.h>
  5.  
  6. int main() 
  7. {
  8.     int N = 10000,i;
  9.     double *z, sum = 0.0, sum_sq = 0.0;
  10.  
  11.  
  12.  
  13.     z = (double *)malloc(N * sizeof(double));
  14.     if (z == NULL) 
  15.     {
  16.         printf("Memory allocation failed!\n");
  17.         return 1;
  18.     }
  19.  
  20.     srand(time(NULL));
  21.  
  22.     for (i = 0; i < N; i += 2) {
  23.         double u1 = (double)rand() / RAND_MAX;
  24.         double u2 = (double)rand() / RAND_MAX;
  25.  
  26.         double r = sqrt(-2.0 * log(u1));
  27.         double theta = 2.0 * 3.14 * u2;
  28.  
  29.         double z1 = r * cos(theta);
  30.         double z2 = r * sin(theta);
  31.  
  32.         z[i] = z1;
  33.         if (i + 1 < N) z[i + 1] = z2;
  34.     }
  35.  
  36.     for (i = 0; i < N; i++) 
  37.     {
  38.         sum += z[i];
  39.         sum_sq += z[i] * z[i];
  40.     }
  41.  
  42.     double mean = sum / N;
  43.     double variance = (sum_sq / N) - (mean * mean);
  44.     double stddev = sqrt(variance);
  45.  
  46.     printf("Generated %d normal random numbers (mean=0, stddev=1)\n", N);
  47.     printf("Mean     = %.6f\n", mean);
  48.     printf("Std Dev  = %.6f\n", stddev);
  49.     free(z);
  50.  
  51.     return 0;
  52. }
Success #stdin #stdout 0.01s 5324KB
comments (?)
stdin 
Standard input is empty
stdout 
Generated 10000 normal random numbers (mean=0, stddev=1)
Mean     = 0.003228
Std Dev  = 0.999080
https://ideone.com/mt98gA
language:
C (gcc 8.3)
created:
6 days ago
visibility:
public

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