1.3.2: signgam problem still present in plotutils, gnuplot etc.

J. Johnston jjohnstn@cygnus.com
Thu Jun 14 09:12:00 GMT 2001

Frank Wuebbeling wrote:
> Hi,
> > Newlib changed math.h in January to have an errno-like solution for
> signgam whereby a function gets
> > called.  Is math.h up to date in the user's Cygwin and is it being
> included by the source code in
> > question?
> Ok. The change to math.h produces my problem, I think. I have a fairly
> recent system, that has been updated using cygwin's setup last week. I'll
> try to illustrate my problem. Here's the shortest code I can come up with:
> #include "math.h"
> main()
> {
>  double a=signgam;
> }
> Use "cc x.c -lm" to compile it. Works without problems on LINUX, for
> example. CYGWIN, in the version I have, gives:
> wuebbel% cc x.c -lm
> /c/FENSTER/TEMP/ccKdCoNl.o(.text+0xc):x.c: undefined reference to
> `__signgam'
> collect2: ld returned 1 exit status

Ok, Frank, I know the problem.  Add -lc to your compile.  The signgam function was placed in the
libc library, not libm.

-- Jeff J.

> That's because *my* math.h contains the lines:
> #ifndef _REENT_ONLY
> #define signgam (*__signgam())
> extern int *__signgam _PARAMS((void));
> #endif /* ! defined (_REENT_ONLY) */
> ...but __signgam is never defined anywhere in the math library. The posting
> I referred to recommended replacing the lines in question in math.h by
> extern __IMPORT struct _reent reent_data;
> #define signgam reent_data._new._reent._gamma_signgam
> which solved my problem. If my math.h is old, then for some reason it's not
> updated by the cygwin setup.
> By the way: The page for the patch you applied in January has a reference to
> changes in math.h, that I can read. Of course, changes in the lib should go
> along with this, but that page is unreachable. Maybe that's why signgam.c
> was left out of the compilation?
> frank

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