- Trending Categories
Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Java Program to Calculate Standard Deviation
In this article, we will understand how to calculate standard deviation. The standard deviation is the measure of how spread-out numbers are. The symbol of standard deviation is sigma( σ ). It is the square root of variance.
Standard deviation is computed using the formula square root of ∑(Xi - ų)2 / N where Xi is the element of the array, ų is mean of the elements of the array, N is the number of elements, ∑ is the sum of the each element.
Problem Statement
Given a program in Java to calculate the standard deviation of a given array of numbers, with the option to either input the array values manually or use a predefined array.
Input
Input Array : [ 35.0, 48.0, 60.0, 71.0, 80.0, 95.0, 130.0 ]
Output
Standard Deviation: 29.313227
Steps to Calculate Standard Deviation
Below are the steps to calculate standard deviation −
- Step 1: START
- Step 2: Declare a double array namely input_array, two doube values namely sum and standard_deviation.
- Step 3: Read the required values from the user/ define the values.
- Step 4: Compute ∑(Xi - ų)2 / N and store the value in result variable.
- Step 5: Display the result
- Step 6: Stop
Example 1
Here, the input is being entered by the user based on a prompt.
public class StandardDeviation {
public static void main(String[] args) {
double[] input_array = { 35, 48, 60, 71, 80, 95, 130};
System.out.println("The elements of the array is defined as");
for (double i : input_array) {
System.out.print(i +" ");
}
double sum = 0.0, standard_deviation = 0.0;
int array_length = input_array.length;
for(double temp : input_array) {
sum += temp;
}
double mean = sum/array_length;
for(double temp: input_array) {
standard_deviation += Math.pow(temp - mean, 2);
}
double result = Math.sqrt(standard_deviation/array_length);
System.out.format("\n\nThe Standard Deviation is: %.6f", result);
}
}
Output
The elements of the array is defined as 35.0 48.0 60.0 71.0 80.0 95.0 130.0 The Standard Deviation is: 29.313227
Example 2
Here, we have defined a function to compute standard deviation.
public class StandardDeviation {
public static void main(String[] args) {
double[] input_array = { 35, 48, 60, 71, 80, 95, 130};
System.out.println("The elements of the array is defined as");
for (double i : input_array) {
System.out.print(i +" ");
}
double standard_deviation = calculateSD(input_array);
System.out.format("\n\nThe Standard Deviation is: %.6f", standard_deviation);
}
public static double calculateSD(double input_array[]) {
double sum = 0.0, standard_deviation = 0.0;
int array_length = input_array.length;
for(double temp : input_array) {
sum += temp;
}
double mean = sum/array_length;
for(double temp: input_array) {
standard_deviation += Math.pow(temp - mean, 2);
}
return Math.sqrt(standard_deviation/array_length);
}
}
Output
The elements of the array is defined as 35.0 48.0 60.0 71.0 80.0 95.0 130.0 The Standard Deviation is: 29.313227
2K+ Views
