Testing for NaN (yes, I know, it has been discussed ad nauseum...)

[Mike McGonagle <mjmogo@...>]

Hi all,

I have been trying to determine how to do this in Lua. I am working on
some Chaotic Attractors, and as such, I need to be able to detect when
a number is "NaN" as a result of these functions, but I can't quite
seem to find exactly how this is done in Lua... one thing that I found
was the following, but I am not certain if this is the "accepted" way,
as one comment said it was not necessarily portable...

if x ~= x then
     -- x is NaN, as if a number is NaN, it will always return false
when being compared.
end

Not trying to dredge up this topic again, but I can't quite seem to
find the "definitive" method of making this test. Currently my
programs are just throwing errors and stopping, I would like to be
able to detect when this happens, discard the results, and then move
on to the next iteration of my program.

Any pointers to where this is discussed in full (I have already seen
http://lua-users.org/wiki/InfAndNanComparisons but this doesn't seem
to give a definitive solution.).

Thank,

Mike