Java.math.BigInteger.modInverse() method in Java

Prerequisite : BigInteger Basics

The modPow() method returns modular multiplicative inverse of this, mod m. This method throws an ArithmeticException if m <= 0 or this has no multiplicative inverse mod m (i.e., gcd(this, m) != 1).

Syntax:



public BigInteger modInverse(BigInteger m)

Parameters: m – the modulus.

Return Value: This method returns a BigInteger object whose value is ((this)^(-1) mod m).

Exception:

  • ArithmeticException – m <= 0, or this BigInteger has no multiplicative inverse mod m (that is, this BigInteger is not relatively prime to m).

Below programs illustrate the BigInteger.modInverse() method:

Program 1 :

filter_none

edit
close

play_arrow

link
brightness_4
code

import java.math.*;
import java.util.Scanner;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        Scanner sc = new Scanner(System.in);
  
        // create 2 BigInteger objects
        BigInteger biginteger1, biginteger2, result;
  
        // Initialize all BigInteger Objects
        biginteger1 = new BigInteger("8");
        biginteger2 = new BigInteger("21");
  
        // perform modInverse operation on biginteger1 using biginteger2.
        result = biginteger1.modInverse(biginteger2);
  
        String expression = biginteger1 + " ^ -1 % "
                            + biginteger2 + " = " + result;
  
        // print result value
        System.out.println(expression);
    }
}

chevron_right


Output:

8 ^ -1 % 21 = 8

Program 2 :

filter_none

edit
close

play_arrow

link
brightness_4
code

import java.math.*;
import java.util.Scanner;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        Scanner sc = new Scanner(System.in);
  
        // create 2 BigInteger objects
        BigInteger biginteger1, biginteger2, result;
  
        // Initialize all BigInteger Objects
        biginteger1 = new BigInteger(88882);
        biginteger2 = new BigInteger(22224);
  
        // perform modInverse operation on biginteger1 using biginteger2.
        result = biginteger1.modInverse(biginteger2);
  
        String expression = biginteger1 + " ^ -1 % "
                            + biginteger2 + " = " + result;
  
        // print result value
        System.out.println(expression);
    }
}

chevron_right


Output :

Exception in thread "main" java.lang.ArithmeticException: BigInteger not invertible.
    at java.math.MutableBigInteger.modInverse(Unknown Source)
    at java.math.MutableBigInteger.mutableModInverse(Unknown Source)
    at java.math.BigInteger.modInverse(Unknown Source)
    at BigInteger.GFG2.main(GFG2.java:23)

Reference: https://docs.oracle.com/javase/7/docs/api/java/math/BigInteger.html#modInverse(java.math.BigInteger)



My Personal Notes arrow_drop_up

I am a Developer I love to code and bring my ideas alive

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.



Improved By : Akanksha_Rai