Java Program to Calculate Standard Deviation

In this program, you’ll learn to calculate the standard deviation using a function in Java.

This program calculates the standard deviation of a individual series using arrays.

To calculate the standard deviation, `calculateSD()` function is created. The array containing 10 elements is passed to the function and this function calculates the standard deviation and returns it to the `main()` function.

Example: Program to Calculate Standard Deviation

1. `public class StandardDeviation {`
2. ` public static void main(String[] args) {`
3. ` double[] numArray = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };`
4. ` double SD = calculateSD(numArray);`
5. ` System.out.format("Standard Deviation = %.6f", SD);`
6. ` }`
7. ` public static double calculateSD(double numArray[])`
8. ` {`
9. ` double sum = 0.0, standardDeviation = 0.0;`
10. ` int length = numArray.length;`
11. ` for(double num : numArray) {`
12. ` sum += num;`
13. ` }`
14. ` double mean = sum/length;`
15. ` for(double num: numArray) {`
16. ` standardDeviation += Math.pow(num - mean, 2);`
17. ` }`
18. ` return Math.sqrt(standardDeviation/length);`
19. ` }`
20. `}`

Note: This program calculates standard deviation of a sample. If you need to compute S.D. of a population, return `Math.sqrt(standardDeviation/(length-1))` instead of `Math.sqrt(standardDeviation/length)` from the `calculateSD()` method.

When you run the program, the output will be:

`Standard Deviation = 2.872281`

In the above program, we’ve used the help of Math.pow() and Math.sqrt() to calculate the power and square root respectively.