.signum()

The Math.signum() method determines whether a number is positive, negative, zero, or NaN.

Math.signum(num)

The .signum() method takes a num parameter and returns a double value that indicates whether num is positive, negative, zero, or NaN.

Some cases to consider include the following:

• If num is positive, a positive non-zero value is returned.
• If num is negative, a negative non-zero value is returned.
• If num is zero, zero is returned.
• If the value of num is NaN, NaN is returned.

The following example demonstrates the .signum() method and its many use cases:

// Test.java
public class Test {
  public static void main(String[] args) {
    System.out.println(Math.signum(8.75));
    System.out.println(Math.signum(-3.5));
    System.out.println(Math.signum(0));
    System.out.println(Math.signum(Double.NaN));
  }
}

This will produce the following output:

1.0
-1.0
0
NaN