Java.lang.StrictMath.ulp() Method



The java.lang.StrictMath.ulp(double d) method returns the size of an ulp of the argument. An ulp of a double value is the positive distance between this floating-point value and the double value next larger in magnitude. For non-NaN x, ulp(-x) == ulp(x).It include these cases −

  • If the argument is NaN, then the result is NaN.
  • If the argument is positive or negative infinity, then the result is positive infinity.
  • If the argument is positive or negative zero, then the result is Double.MIN_VALUE.
  • If the argument is ±Double.MAX_VALUE, then the result is equal to 2971.


Following is the declaration for java.lang.StrictMath.ulp() method

public static double ulp(double d)


d − This is the floating-point value whose ulp is to be returned.

Return Value

This method returns the size of an ulp of the argument.




The following example shows the usage of java.lang.StrictMath.ulp() method.

package com.tutorialspoint;

import java.lang.*;

public class StrictMathDemo {

   public static void main(String[] args) {

      double d1 = 5.5 , d2 = -2.9, d3 = 0.0;
      // returns the size of an ulp of the argument
      double ulpValue = StrictMath.ulp(d1); 
      System.out.println("Size of ulp of " + d1 + " = " + ulpValue);
      ulpValue = StrictMath.ulp(d2); 
      System.out.println("Size of ulp of " + d2 + " = " + ulpValue);
      ulpValue = StrictMath.ulp(d3); 
      System.out.println("Size of ulp of " + d3 + " = " + ulpValue);

Let us compile and run the above program, this will produce the following result −

Size of ulp of 5.5 = 8.881784197001252E-16
Size of ulp of -2.9 = 4.440892098500626E-16
Size of ulp of 0.0 = 4.9E-324