The code below show you how to get the signum function of a number using the Math.signum() static method call. This method extracts the sign of a real number. If you have a number of x the signum function of x is -1 if x < 0; 0 if x = 0 and 1 if x > 0.
package org.kodejava.example.math;
public class SignumExample {
public static void main(String[] args) {
Double zero = 0.0D;
Double negative = -25.0D;
Double positive = 15.0D;
//
// Get the signum function of value of a number.
// It returns:
// * 0 if the value is zero.
// * 1.0 if value is greater than zero.
// * -1.0 if value is less than zero.
//
double sign1 = Math.signum(zero);
double sign2 = Math.signum(negative);
double sign3 = Math.signum(positive);
//
// For floating-point value
//
float sign4 = Math.signum(zero.floatValue());
float sign5 = Math.signum(negative.floatValue());
float sign6 = Math.signum(positive.floatValue());
System.out.println("In double:");
System.out.println("Signum of " + zero + " is " + sign1);
System.out.println("Signum of " + negative + " is " + sign2);
System.out.println("Signum of " + positive + " is " + sign3);
System.out.println("In float:");
System.out.println("Signum of " + zero + " is " + sign4);
System.out.println("Signum of " + negative + " is " + sign5);
System.out.println("Signum of " + positive + " is " + sign6);
}
}
Here is the output of the program:
In double:
Signum of 0.0 is 0.0
Signum of -25.0 is -1.0
Signum of 15.0 is 1.0
In float:
Signum of 0.0 is 0.0
Signum of -25.0 is -1.0
Signum of 15.0 is 1.0