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The Laws of Cryptography with Java Code.

Java supplies a function to calculate natural logs, base e = 2.718281828459045. To calculate logs to other bases, you need to multiply by a fixed constant: for a log base b multiply by 1/log_eb

// Logs.java: try out logarithm formulas
public class Logs {

   // main function to try out Logs class
   public static void main (String[] args) {
      System.out.println("log base 2 of 1024 = " + log2(1024));
      System.out.println("log base 10 of 1000 = " + log10(1000));
      System.out.println("log 2 = " + Math.log(2));
      System.out.println("1/log 2 = " + 1/Math.log(2));
      System.out.println("log base 10 of 2 = " + log10(2));
   } // end of main

   // log2:  Logarithm base 2
   public static double log2(double d) {
      return Math.log(d)/Math.log(2.0);
   }

   // log10: Logarithm base 10
   public static double log10(double d) {
      return Math.log(d)/Math.log(10.0);
   }
} 
 
/* Output:
         
log base 2 of 1024 = 10.0
log base 10 of 1000 = 2.9999999999999996
log 2 = 0.6931471805599453
1/log 2 = 1.4426950408889634
log base 10 of 2 = 0.30102999566398114

*/