Bigdecimal logarithm in Java

Question

I want to calculate the logarithm of the transmitter.getETXPOW(), what is BigDecimal format.

BigDecimal power =  transmitter.getETXPOW();
BigDecimal eirp = 10 * Math.log(power);

I received an error message, BigDecimal can not be converted to double.

Logarithm base is 10.

You're passing `power` to the `Math.log()` method, which takes a `double`, not a `BigDecimal`. — chiastic-security, Sep 17 '14 at 21:33
See http://stackoverflow.com/questions/739532/logarithm-of-a-bigdecimal?rq=1 — user1071777, Sep 17 '14 at 21:34
For completeness - `Math.log` is the natural log. `Math.log10` is what you want to use if you want a base-10 log. You could always do a change-of-base operation if you really needed to, as well. — Makoto, Sep 17 '14 at 21:36

score 1 · Answer 1 · answered Sep 17 '14 at 21:35

To convert to double value use BigDecimal class doubleValue(). See demo

import java.math.*;

public class BigDecimalDemo {

   public static void main(String[] args) {

      // create a BigDecimal object
      BigDecimal bg;

      // create a Double object
      Double d;

      bg=new BigDecimal("1234");

      // assign the converted value of bg to d
      d=bg.doubleValue();

      String str = "Double value of " + bg + " is " + d;

      // print d value
      System.out.println( str );
   }
}

Bigdecimal logarithm in Java

1 Answers1