How to Calculate Standard Deviation by Java Program

July 28, 2023

Java Program to Calculate Standard Deviation.

Java Array and Methods.

  • An object of a class that is dynamically produced in Java is an array. Java array implements the Serializable and Cloneable interfaces and derives from the Object class. The first element of an array is stored at index 0, the second member is kept at index 1, and so forth. Arrays in Java are index-based.
  • A method in Java is a section of code that completes a certain task. Code can be contained in methods, which makes it more reusable and understandable.Java methods make it simpler to build and maintain complicated programmes by giving coders a means to organise and reuse code.

To know more about Java Program to calculate Standard Deviation read the complete article.

Steps to Calculate Standard Deviation by Java Program

  • Here are the steps to calculate the standard deviation in Java:

    • First, you need to find the mean (average) of the data set.

    • Then, subtract the mean from each data point to find the deviations.

    • Square each deviation to remove the negative sign.

    • Find the sum of all the squared deviations.

    • Divide the sum by the number of data points minus one (n-1).

  • Take the square root of the result to find the standard deviation.

Introduction to java

Inheritance in java 

Wrapper classes in Java 

Methods in Java 

Arrays: 1D and 2D

Let’s look at a Java Program to calculate Standard Deviation to perform certain operations.

Example 1: Java Program to Calculate standard Deviation.

Run 
import java.util.Arrays;

public class Main {
  public static void main(String[] args) {
    double[] input = {10, 20, 35, 40, 45};
    double sum = 0, mean;
    int n = input.length;

    for (int i = 0; i < n; i++) {
      sum += input[i];
    }
    mean = sum / n;
    System.out.println("Mean: " + mean);

    sum = 0;
    for (int i = 0; i < n; i++) {
      sum += Math.pow(input[i] - mean, 2);
    }
    mean = sum / (n - 1);
    double deviation = Math.sqrt(mean);
    System.out.println("Standard deviation: " + deviation);
  }
}

Output

Mean: 15.0
Standard deviation: 7.0710678118654755
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Example 2 : Java Program to Calculate Standard Deviation 

Run 
class Main 
{
   public static void main(String args[]) 
    { 
	double[] input={5,10,15,20,25};
	double n=5,sum=0,mean;
	for(int i=0;i<n;i++) 
	{
		sum=sum+input[i];
	}
	mean=sum/n;
       	System.out.println("Mean :"+mean);
	sum=0;  
	for(int i=0;i<n;i++) 
	{
		sum+=Math.pow((input[i]-mean),2);
	
	}
	mean=sum/(n-1);
	double deviation=Math.sqrt(mean);
	System.out.println("standard deviation :"+deviation);

   }
}

Output

Mean :15.0
standard deviation :7.905694150420948

Example 3: Java Program to Calculate Standard Deviation: 

Run 
import java.util.Arrays;

public class Main {
  public static double calculateSD(double numArray[]) {
    double sum = 0.0, standardDeviation = 0.0;
    int length = numArray.length;

    for (double num : numArray) {
      sum += num;
    }

    double mean = sum / length;

    for (double num : numArray) {
      standardDeviation += Math.pow(num - mean, 2);
    }

    return Math.sqrt(standardDeviation / length);
  }

  public static void main(String[] args) {
    double[] numArray = {1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0};
    System.out.format("Standard Deviation = %.6f", calculateSD(numArray));
  }
}

Output

Standard Deviation = 2.581989

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