C Program to Calculate Standard Deviation

This program calculates the standard deviation of an individual series using arrays. Visit this page to learn about Standard Deviation.

To calculate the standard deviation, we have created a function named calculateSD().

Example: Population Standard Deviation

// SD of a population
#include <math.h>
#include <stdio.h>
float calculateSD(float data[]);
int main() {
    int i;
    float data[10];
    printf("Enter 10 elements: ");
    for (i = 0; i < 10; ++i)
        scanf("%f", &data[i]);
    printf("\nStandard Deviation = %.6f", calculateSD(data));
    return 0;
}

float calculateSD(float data[]) {
    float sum = 0.0, mean, SD = 0.0;
    int i;
    for (i = 0; i < 10; ++i) {
        sum += data[i];
    }
    mean = sum / 10;
    for (i = 0; i < 10; ++i) {
        SD += pow(data[i] - mean, 2);
    }
    return sqrt(SD / 10);
}

Output

Enter 10 elements: 1
2
3
4
5
6
7
8
9
10

Standard Deviation = 2.872281

Here, the array containing 10 elements is passed to the calculateSD() function. The function calculates the standard deviation using mean and returns it.

Note: The program calculates the standard deviation of a population. If you need to find the standard deviation of a sample, the formula is slightly different.