Finding if a number is 'NaN'

I should have been able to find this in existing support messages. But the search engine here doesn't allow for phrase searches. Grr.

How do you find if a variable is not a number (NaN)?

Thanks, FoxRings. =)

go to variable functions section in the manual.
Next time don't just search the forum actually look in the manual.

Ace21

Actually I usually search the manual first(as is the case here).

Thank you for pointing out where in the manual to find that.

I suppose after I get a little more familiar with the manual I will be able to find what I am looking for without the engine finding it for me.

Thank again, Mike