c语言求和与平均值（编程求均值和标准差）

计算C语言中的求和、标准差、方差和标准差等，需要加上头文件：#include <math.h>

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 #include<stdio.h> #include "math.h" double sum = 0;//求和 double array[4] = {1.2,2.1,3.1,4.1}; int length = 0;//数组长度 double average = 0;//求平均数 double var = 0; //求方差 double standard = 0; //求标准差 int main() { for (int i = 0; i <= 3;i++) { sum += array[i];//求和 } length = sizeof(array) / sizeof(array[0]);//求数组长度 average = sum / length;//求平均值 for (int j = 0; j <= 3;j++) { var += pow(array[j]-average,2)/length;//求方差 } standard = pow(var,0.5);//求标准差 printf("sum = %g\n",sum);//这边打印也可以使用printf("%f\n",sum);这种打印默认出来的数是小数点后6位 printf("length of array[4] = %d\n",length); printf("average = %g\n",average); printf("var = %g\n",var); printf("standard = %g\n",standard); while (1); return 0; }

补充知识：C语言：计算并输出给定10个数的方差

//计算并输出给定10个数的方差。

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 #include<math.h> #include<stdio.h> double fun(double x[10]) { double p = 0.0,f=0.0,g=0.0; for (int i = 0; i < 10; i++) { p += x[i]; } p = p / 10; printf("%f\n", p); for (int j = 0; j < 10; j++) { g = x[j] - p; f += g*g; printf("%f\n", f); } f = f / 10; f = sqrt(f); return f; } void main() { FILE *wf; double s,x[10]={95.0,89.0,76.0,65.0,88.0,72.0,85.0,81.0,90.0,56.0}; int i; printf("\nThe original data is:\n"); for(i=0;i<10;i++) printf("%6.1f ",x[i]); printf("\n\n "); s=fun(x); printf("s=%f\n\n ",s); /******************************/ wf=fopen("out.dat","w"); fprintf(wf,"%f",s); fclose(wf); /*****************************/ }