In java what does NaN mean?

Question:

What does NaN mean in java?

Answer:

Not A Number

Here are a few examples on how to generate (trigger) a NaN:

Code:

public class NaN {
  public static void main(String[] args) {
 
    Double d1 = 0d/0d;
    System.out.println("d1: "  + d1);
 
    Double d2 = Double.POSITIVE_INFINITY / Double.POSITIVE_INFINITY;
    System.out.println("d2: "  + d2);
 
    Double d3 = 0d *  Double.POSITIVE_INFINITY;
    System.out.println("d3: "  + d3);
 
    Double d4 = Math.pow(1, Double.POSITIVE_INFINITY);
    System.out.println("d4: "  + d4);
 
    Double d5 = Double.POSITIVE_INFINITY + Double.NEGATIVE_INFINITY;
    System.out.println("d5: "  + d5);
 
    Float f1 = Float.POSITIVE_INFINITY - Float.POSITIVE_INFINITY;
    System.out.println("f1: "  + f1);
 
  }
}

Output:

$ java NaN
d1: NaN
d2: NaN
d3: NaN
d4: NaN
d5: NaN
f1: NaN