In Java, what does NaN mean?

Question

I have a program that tries to shrink a double down to a desired number. The output I get is NaN.

What does NaN mean in Java?<

Answer 1

NaN means "Not a Number" and is the result of undefined operations on floating point numbers like for example dividing zero by zero. (Note that while dividing a non-zero number by zero is also usually undefined in mathematics, it does not result in NaN but in positive or negative infinity).