[Bug libfortran/33683] calculating lgamma instead of gamma

["tkoenig at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #3 from tkoenig at gcc dot gnu dot org  2007-10-07 10:22 -------
(In reply to comment #2)
> I checked and the simplification routines work correctly, which means there is
> no real testsuite coverage for these functions. We should always include
> testcases comparing values calculated at runtime with constants coming from our
> simplification routines.

I concur.  PR 22307 strikes again...

The cause of the problem is outlined in the gamma(3) man page
of my Linux distro:

DESCRIPTION
       For the definition of the Gamma function, see tgamma(3).

   *BSD version
       4.4BSD and FreeBSD libm have a gamma() function that computes the Gamma
       function, as one would expect.

   glibc version
       Glibc has a gamma() function that is equivalent to  lgamma()  and  com-
       putes  the  natural logarithm of the Gamma function.  (This is for com-
       patibility reasons only.  Don't use this function.)

CONFORMING TO
       4.2BSD.  Compatible with previous mistakes.

I think we need to use tgamma() where available.  If it isn't, we
need a test to check whether gamma() is equivalent to tgamma() or
to lgamma().

Yuck.


-- 

tkoenig at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-10-07 10:22:12
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33683