[Bug middle-end/29335] transcendental functions with constant arguments should be resolved at compile-time

["sgk at troutmask dot apl dot washington dot edu" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #17 from sgk at troutmask dot apl dot washington dot edu  2006-10-28 03:48 -------
Subject: Re:  transcendental functions with constant arguments should be
resolved at compile-time

On Sat, Oct 28, 2006 at 03:20:11AM -0000, ghazi at gcc dot gnu dot org wrote:
> 
> 
> ------- Comment #16 from ghazi at gcc dot gnu dot org  2006-10-28 03:20 -------
> I'm getting wierd NaN results when I hook up __builtin_lgamma to mpfr_lngamma. 
> I can expose the problem using a standlone C program calling mpfr like so. 
> Results are first, C testcase is second.  Now I know lgamma/mpfr_lngamma are
> both documented to barf on negative integers.  But as you can see, I'm passing
> x.5 in every case.  Seems like any time "x" is an even number I get a NaN.  I
> wonder if this is a bug in mpfr, or my mistake?  (I tried mpfr-2.2.0 with and
> without the cumulative patch.  I got the problem in both cases.)  Can anyone
> else reproduce this?
> 
> lgamma(-4.50) = -2.813084
> mpfr_lngamma(-4.50) = @NaN@
> 

Yes, I can reproduce the NaN.  In fact, any negative value 
gives a NaN.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29335