Re: Some small requests for the next release

[David Jones <drj@...>]

On Feb 27, 2005, at 01:36, Luiz Henrique de Figueiredo wrote:

> > 1) Add 'math.nan' as a constant to the math library.  At the moment, 
> > the
> > "feature" of doing
> >        local nan = tonumber("nan")
> >     works, but is inconvenient, probably non portable and hard to 
> > remember.
>
> A more portable solution is something like "nan = math.sqrt(-1)", but
> that relies on IEEE 754. Perhaps an IEEE 754 library would be a good
> idea (I have a draft of one but it's not complete and it's not 
> portable,
> not even among platforms that claim to be IEEE 754. C99 helps here but
> it's not widespread yet.)

nan = tonumber"nan" will do, it's not very non-portable.  On an IEEE 
conforming system this will generate a NaN.  On systems without NaNs 
then it will generate 0.  Seems like a reasonable behaviour.  You can 
even do [[ if nan == nan ]] to see which one you ended up with.

Why would anyone anyone want math.nan anyhow?  Surely they get 
generated naturally as the result of ordinary computation.

David Jones