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

[Mike McGonagle <mjmogo@...>]

so, does it really have a '-' in front? on a mac, it just returns
'nan' for tostring(x) with 'x' being "not a number"...

On Sat, Nov 6, 2010 at 12:19 PM, HyperHacker <hyperhacker@gmail.com> wrote:
> On Sat, Nov 6, 2010 at 08:08, Mike McGonagle <mjmogo@gmail.com> wrote:
>> 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
>>
>>
>
> tostring(n)? Though I'm seeing "-nan" for 0/0.
>
> --
> Sent from my toaster.
>
>