Calculating powers of integers

Question

Is there any other way in Java to calculate a power of an integer?

I use Math.pow(a, b) now, but it returns a double, and that is usually a

Answer 1

Best the algorithm is based on the recursive power definition of a^b.

long pow (long a, int b)
{
    if ( b == 0)        return 1;
    if ( b == 1)        return a;
    if (isEven( b ))    return     pow ( a * a, b/2); //even a=(a^2)^b/2
    else                return a * pow ( a * a, b/2); //odd  a=a*(a^2)^b/2

}

Running time of the operation is O(logb). Reference:More information

Answer 2

base is the number that you want to power up, n is the power, we return 1 if n is 0, and we return the base if the n is 1, if the conditions are not met, we use the formula base*(powerN(base,n-1)) eg: 2 raised to to using this formula is : 2(base)*2(powerN(base,n-1)).

public int power(int base, int n){
   return n == 0 ? 1 : (n == 1 ? base : base*(power(base,n-1)));
}

Answer 3

Apache has ArithmeticUtils.pow(int k, int e).

Answer 4

Unlike Python (where powers can be calculated by a**b) , JAVA has no such shortcut way of accomplishing the result of the power of two numbers. Java has function named pow in the Math class, which returns a Double value

double pow(double base, double exponent)

But you can also calculate powers of integer using the same function. In the following program I did the same and finally I am converting the result into an integer (typecasting). Follow the example:

import java.util.*;
import java.lang.*; // CONTAINS THE Math library
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n= sc.nextInt(); // Accept integer n
        int m = sc.nextInt(); // Accept integer m
        int ans = (int) Math.pow(n,m); // Calculates n ^ m
        System.out.println(ans); // prints answers
    }
}

Alternatively, The java.math.BigInteger.pow(int exponent) returns a BigInteger whose value is (this^exponent). The exponent is an integer rather than a BigInteger. Example:

import java.math.*;
public class BigIntegerDemo {
public static void main(String[] args) {
      BigInteger bi1, bi2; // create 2 BigInteger objects          
      int exponent = 2; // create and assign value to exponent
      // assign value to bi1
      bi1 = new BigInteger("6");
      // perform pow operation on bi1 using exponent
      bi2 = bi1.pow(exponent);
      String str = "Result is " + bi1 + "^" +exponent+ " = " +bi2;
      // print bi2 value
      System.out.println( str );
   }
}