Java Program to Implement Repeated Squaring Algorithm

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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.

  1. /**
  2.  ** Java Program to Implement Repeated Squaring Algorithm
  3.  **/
  4.  
  5. import java.util.Scanner;
  6.  
  7. /** Class RepeatedSquaring **/
  8. public class RepeatedSquaring
  9. {
  10.     /** Function for repeated squaring **/
  11.     public double expBySquaring(double x, int n)
  12.     {
  13.         if (n < 0)
  14.             return expBySquaring(1 / x, -n);
  15.         else if (n == 0)
  16.             return 1;
  17.         else if (n == 1)
  18.             return x;
  19.         else if (n % 2 == 0)
  20.             return expBySquaring(x * x, n / 2);
  21.         else 
  22.             return x * expBySquaring(x * x, (n - 1)/2);    
  23.     }
  24.     /** Main function **/
  25.     public static void main (String[] args) 
  26.     {
  27.         Scanner scan = new Scanner(System.in);
  28.         System.out.println("Repeated Squaring Algorithm Test\n");
  29.         /** Make an object of RepeatedSquaring class **/
  30.         RepeatedSquaring rs = new RepeatedSquaring();
  31.  
  32.         /** Accept n , k **/
  33.         System.out.println("\nEnter n and k of (N ^ K)");
  34.         double n = scan.nextDouble();
  35.         int k = scan.nextInt();
  36.         double result = rs.expBySquaring(n, k);
  37.  
  38.         System.out.println("\nResult : "+ result);        
  39.     }
  40. }

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

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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