毛哥資訊日誌

#include "stdlib.h"

float mean(int n, float sample[]) //算平均
{
 float sum = 0.0;
 for(int i=0; i<n; i++) sum += sample[i];
 return(sum/n);
}

float var(int n, float sample[]) //標準差
{
 float sum = 0.0;
 float u = mean(n, sample);

 for(int i=0; i<n; i++) sum += (sample[i]-u) * (sample[i]-u);
 return(sum/n);
}
float u_rand() // 0 ~ 1
{
 return (float)rand()/RAND_MAX;
}

float n_rand() // 平均 0
{
 float sum = 0.0;

 for(int i=0; i<12; i++) sum += u_rand();
 return(sum-6);
}

float t_rand(int n, float u, float s) //漁夫 n->數量
{
 float *sample;

 sample = new float[n];

 for(int i=0; i<n; i++)
 {
  sample[i] = n_rand() * s + u;
 }
 
 return(mean(n, sample));
}

float f_rand(int k, int n,float u, float s) //可信度 u->平均值 s->標準差
{
 float *sample;
 float *group_mean;

 sample = new float [k*n];
 group_mean = new float [k];

 for(int i=0; i<k; i++)
 {
  for(int j=0; j<n; j++) sample[i*n+j ] = n_rand()*s+u;
  group_mean[i] = mean(n, sample + i*n);
 }
 float total_var = var(k, group_mean);
 delete group_mean;
 delete sample;
 return(total_var);
}