Re: tostring vs. nan, inf

[liam mail <liam.list@...>]

On 10 April 2012 13:13, Martin Guy <martinwguy@gmail.com> wrote:
> On 10 April 2012 13:38, Alexander Gladysh <agladysh@gmail.com> wrote:
>> On Tue, Apr 10, 2012 at 14:58, Luiz Henrique de Figueiredo
>> <lhf@tecgraf.puc-rio.br> wrote:
>>>> one can simply define them as global variables
>>>
>>> This seems to me to be a good compromise if you want to convert those
>>> values frequently.
>>
>> Wouldn't work for Windows ( 1.#INF) with stock Lua.
>
> So your local solution seems to be to redefine tostring() to trap
> these three values and print something that will regenerate them.  On
> this implementation (Linux/x86) that seems to be possible with inf and
> -inf but I don't see how to detect nan portably.
>
> inf = 1/0
> nan = 0/0
> print( inf == inf)
> true
> print( nan == nan )
> false
>

Hehe that is how you detect nan, it is never equal to itself; also
don't forget negative infinity -1/0.0

Liam