Re: patch for gamma test

[Marco Atzeri]

--- Mer 17/11/10, Tatsuro MATSUOKA  ha scritto:

> Hello
> 
> 
> Seeing code of the implementation of slatex gamma, in that
> case, gamma(-1)=Inf is condiderd.
> 
>  
> liboctave/lo-specfun.cc
> 
> double
> xgamma (double x)
> {
> #if defined (HAVE_TGAMMA)
>   return tgamma (x);

on cywin HAVE_TGAMMA=1


> #else
>   double result;
> 
>   if (xisnan (x))
>     result = x;
>   else if ((x <= 0 && D_NINT (x) == x) ||
> xisinf (x))
>     result = octave_Inf;
>   else
>     F77_XFCN (xdgamma, XDGAMMA, (x, result));
> 
>   return result;
> #endif
> }
> 
> 
> From the part
>   else if ((x <= 0 && D_NINT (x) == x) ||
> xisinf (x))
>     result = octave_Inf;
> 
> it is obvious that implementation of slatec gamma function
> shows gamma(-1)=inf
> 
> I think that lo-specfun.cc code or configure check
> should  be changed that gamma(minus integer) does
> not depend on the environments.

If the slatec function is correct than only some 
external tgamma are wrong.
In any case it is better to report a failure on that platform
and eventually report the failure upstream than
as today where the fail is wrongly reported on the 
correct platform.

I doubt it is worth to check gamma(-1) during configuration.

Marco