Java BigInteger modPow() method

The modPow() method of Java BigInteger class is used to perform modular exponentiation. This method returns a BigInteger whose value is (this^exponent mod parameter value). This method first calculates the pow() method then applies the mod() method. This method allows negative exponents.

Syntax:

Parameter:

exponent- The Exponent.

m- The modulus.

Returns:

This method returns (this^exponent mod m).

Exception:

ArithmeticException - m ≤ 0

Example 1

import java.math.BigInteger;
public class BigIntegerModPowExample1 {
	public static void main(String[] args) {
		//create 4 BigInteger objects 
		BigInteger big1,big2,exp,result;
		// initialize all BigInteger objects
		big1=new BigInteger("13");
		big2=new BigInteger("5");
		exp=new BigInteger("2");
                     //perform modPow operation on big1 using big2 and exp
		result=big1.modPow(exp,big2);
		String str=big1+"^"+exp+" mod "+big2+" is "+result;
		System.out.println(str);
	}
}

Test it Now

Output:

13^2 mod 5 is 4

Example 2

import java.math.BigInteger;
public class BigIntegerModPowExample2 {
	public static void main(String[] args) {
		//create 4 BigInteger objects 
		BigInteger big1,big2,exp,result;
		// initialize all BigInteger objects
		big1=new BigInteger("13");
		big2=new BigInteger("-5");
		exp=new BigInteger("2");
                     //perform modPow operation on big1 using big2 and exp
		result=big1.modPow(exp,big2);
		String str=big1+"^"+exp+" mod "+big2+" is "+result;
		System.out.println(str);
	}
}

Test it Now

Output:

java.lang.ArithmeticException: BigInteger: modulus not positive

Example 3

import java.math.BigInteger;
public class BigIntegerModPowExample3 {
	public static void main(String[] args) {
		//create 4 BigInteger objects 
		BigInteger big1,big2,exp,result;
		// initialize all BigInteger objects
		big1=new BigInteger("13");
		big2=new BigInteger("5");
		exp=new BigInteger("-2");
                     //perform modPow operation on big1 using big2 and exp
		result=big1.modPow(exp,big2);
		String str=big1+"^"+exp+" mod "+big2+" is "+result;
		System.out.println(str);
	}
}

Test it Now

Output:

13^-2 mod 5 is 4

Example 4

import java.math.BigInteger;
public class BigIntegerModPowExample4 {
	public static void main(String[] args) {
		//create 4 BigInteger objects 
		BigInteger big1,big2,exp,result;
		// initialize all BigInteger objects
		big1=new BigInteger("-13");
		big2=new BigInteger("5");
		exp=new BigInteger("-2");
                     //perform modPow operation on big1 using big2 and exp
		result=big1.modPow(exp,big2);
		String str=big1+"^"+exp+" mod "+big2+" is "+result;
		System.out.println(str);
	}
}

Test it Now

Output: