User-Defined Functions

Write a program to calculate the standard deviation of an array of values. Thea array elements are read from the terminal. Use functions to calculate standard deviation and mean.

#include <stdio.h>
#include <math.h>
#define SIZE 5
   float std_dev(float a[], int n);
   float mean (float a[], int n);
void main( )
   {
        float value[SIZE];
        int i;                                                
                                                              
        printf("Enter %d float values\n", SIZE);              
        for (i=0 ;i < SIZE ; i++)                             
            scanf("%f", &value[i]);                           
        printf("Std.deviation is %f\n", std_dev(value,SIZE)); 
 getch();
   }
   float std_dev(float a[], int n)                                         
   {    int i;                                                
        float x, sum = 0.0;                           
        x = mean (a,n);                                       
        for(i=0; i < n; i++)                                   
         sum += (x-a[i])*(x-a[i]);                             
        return(sqrt(sum/(float)n));                           
   }                                                          
   float mean(float a[],int n)                                            
   {                                                          
        int i ;                                               
        float sum = 0.0;                                      
        for(i=0 ; i < n ; i++)                                
           sum = sum + a[i];                                  
        return(sum/(float)n);                                 
   }