[Discuss] Test for positive gives wacko results for underflowed values for the gcc compiler suite (including the gcc compiler, and g77 and gfortran compilers)

[Alan W. Irwin]

On 2007-06-25 14:12-0700 pw wrote:

> Alan W. Irwin wrote:
>> Is this a gcc (and g77 and gfortran) issue?  I would appreciate it if
>> somebody would run the above C test codes with different C
>> compilers/platforms.
>> 
>> Alan
>
>
> I get the same thing.
>
> Intel core duo:
>
> gfortran -v
> Using built-in specs.
> Target: i386-pc-mingw32
> Configured with: ../trunk/configure --prefix=/mingw 
> --enable-languages=c,fortran --with-gmp=/home/coudert/local --disable-nls 
> --with-ld=/mingw/bin/ld --with-as=/mingw/bin/as --disable-werror 
> --enable-bootstrap --enable-threads --build=i386-pc-mingw32 --disable-shared 
> --enable-libgomp
> Thread model: win32
> gcc version 4.3.0 20070522 (experimental)

Thanks, Peter, for confirming the problem still exists for modern (version
4.3.0) gfortran.

I should have said that on my Ubuntu system my gfortran version is "GNU
Fortran 95 (GCC 4.0.3 (Ubuntu 4.0.3-1ubuntu5))" while my gcc version is "gcc
(GCC) 4.0.3 (Ubuntu 4.0.3-1ubuntu5)".

I also get the same bad results on my Debian sarge system which has g77
version "GNU Fortran (GCC) 3.3.5 (Debian 1:3.3.5-13)" and gcc version
"gcc (GCC) 3.3.5 (Debian 1:3.3.5-13)".

Python gives the correct results both on my Ubuntu system
(Python 2.4.3) and my older Debian system (Python 2.3.5).

Does anybody have access to non-gcc fortran or C compilers (such as the Intel
ones)?  A non-gcc test result would be most interesting.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
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