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How to calculate log base 2 of an Integer in Java?

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  • Difficulty Level : Easy
  • Last Updated : 11 Mar, 2022
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Given an integer N, the task is to calculate its log to the base 2, i.e. log2 N in Java.

Examples: 

Input: N = 2
Output: 1

Input: 1024
Output: 10

Approach: 

        loga b = loge b / loge a
  • Therefore we can calculate log2 N indirectly as:
        log2 N = loge N / loge 2

Below is the implementation of the above approach:

Java




// Java code to Calculate log base 2 of an integer
 
import java.io.*;
import java.lang.*;
 
class GFG {
 
    // Function to calculate the
    // log base 2 of an integer
    public static int log2(int N)
    {
 
        // calculate log2 N indirectly
        // using log() method
        int result = (int)(Math.log(N) / Math.log(2));
 
        return result;
    }
 
    // Driver code
    public static void main(String[] args)
    {
 
        int N = 1024;
 
        System.out.println("Log " + N + " to the base 2 = " + log2(N));
    }
}

Output: 

Log 1024 to the base 2 = 10

 

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