[Ffmpeg-devel] [PATCH] Redefine NAN in eval.c

[Rich Felker]

On Sat, Sep 23, 2006 at 05:33:07PM +0100, M?ns Rullg?rd wrote:
> Rich Felker <dalias at aerifal.cx> writes:
> 
> > On Sat, Sep 23, 2006 at 02:13:14AM +0200, Michael Niedermayer wrote:
> >> Hi
> >> 
> >> On Fri, Sep 22, 2006 at 11:35:36PM +0200, Panagiotis Issaris wrote:
> >> > Hi,
> >> > 
> >> > In the process of modifying the AVOptions code to use eval.c I noticed
> >> > that I could not report a failed parsing, as ff_eval returned 0 not NAN.
> >> > The attached patch, defines NAN -if not already defined as f.e. in C99-
> >> > to be sqrt(-1) in the scope of eval.c. Regression tests succeed.
> >> 
> >> iam fine with 0.0/0.0
> >
> > 0.0/0.0 is correct. sqrt(-1) is not a constant and thus it's nonsense.
> > Also you can define a non-exception-raising NAN using unions; this
> > might be preferable but it requires C99 and IEEE float.
> 
> C99 already requires NAN to be defined.

IIRC it's only required if NAN makes sense/if the host implements IEEE
float. ISO C is very lax about floating point requirements unless your
implementation claims conformance to additional standards. However I
may be mistaken on this one.

Anyway your point is well-taken. :)

Rich