How to check whether a number is a "NaN" in java / android?

How to check whether a number is a "NaN" in java / android?

Please have a look at the following code
private List createTheDynamicWordList(String algorithm, double averageStat)
{
Toast.makeText(context, ""+averageStat, Toast.LENGTH_LONG).show();
}
in some cases, I get the averageStat as a 'NaN' value. I need to check
whether the number if 'NaN' ir not. How can I do this? Using
NumberFormatException here didn't work. Please help.