Java Program to Implement Repeated Squaring Algorithm

This is a Java Program to Implement Repeated Squaring Algorithm. Repeated squaring algorithm is used to compute xⁿ efficiently.

Here is the source code of the Java Program to Implement Repeated Squaring Algorithm. The Java program is successfully compiled and run on a Windows system. The program output is also shown below.

/**
 ** Java Program to Implement Repeated Squaring Algorithm
 **/
 
import java.util.Scanner;
 
/** Class RepeatedSquaring **/
public class RepeatedSquaring
{
    /** Function for repeated squaring **/
    public double expBySquaring(double x, int n)
    {
        if (n < 0)
            return expBySquaring(1 / x, -n);
        else if (n == 0)
            return 1;
        else if (n == 1)
            return x;
        else if (n % 2 == 0)
            return expBySquaring(x * x, n / 2);
        else 
            return x * expBySquaring(x * x, (n - 1)/2);    
    }
    /** Main function **/
    public static void main (String[] args) 
    {
        Scanner scan = new Scanner(System.in);
        System.out.println("Repeated Squaring Algorithm Test\n");
        /** Make an object of RepeatedSquaring class **/
        RepeatedSquaring rs = new RepeatedSquaring();
 
        /** Accept n , k **/
        System.out.println("\nEnter n and k of (N ^ K)");
        double n = scan.nextDouble();
        int k = scan.nextInt();
        double result = rs.expBySquaring(n, k);
 
        System.out.println("\nResult : "+ result);        
    }
}

Output:

Repeated Squaring Algorithm Test
 
 
Enter n and k of (N ^ K)
3 19
 
Result : 1.162261467E9
 
 
Repeated Squaring Algorithm Test
 
 
Enter n and k of (N ^ K)
7 -4
 
Result : 4.1649312786339016E-4