Is there any way to check float/double for NaN? I can't find any.

I've checked standard C way - its not working:

if (fValue ≠ fValue)

Also I can't find any special function.

MrK45 said:
if (fValue ≠ fValue)

Does not work for me either anymore, since some years.
But there are related STL functions, for example:

#include <cmath>

if (!std::isfinite(fValue))

In modern C standards there is

bool std::isnan(fValue)

But I'm asking about solution for Angelscript…

There is no built-in way for checking for NaN. But you can easiliy register a function for it.