[Numpy-discussion] Unhandled floating point exception running test in numpy-1.0.3 and svn 3875

Charles R Harris charlesr.harris at gmail.com
Sun Jun 24 03:54:51 EDT 2007


On 6/23/07, rex <rex at nosyntax.com> wrote:
>
> Stefan van der Walt <stefan at sun.ac.za> [2007-06-23 15:06]:
> >
> > On Sat, Jun 23, 2007 at 07:35:35PM +0000, John Ollinger wrote:
> > >
> > > I have just been updating our version of Python, numpy and scipy and
> have run
> > > into a floating point exception that crashes Python when I test the
> release.
> > >


What do you mean by crash? Is anything printed? Do older versions of numpy
still work?

> > I am running gcc 3.3.1 on SuSe Linux 2.4.21-144-smp4G.  The error first
> occurred
> > > with numpy-1.0.3.  I downloaded svn 3875 when I then read the scipy
> web page and
> > > installed the latest subversion. The test command I am using is
> > >
> > > python -c 'import numpy; numpy.test(level=1,verbosity==2)'
> > >
> > > and occurs during the matvec test.  This test uses rand to generate
> > > 10x8 and 8x1
> >
> > It may be worth checking whether the new version of numpy is picked
> > up.  You can do that using
> >
> > import numpy as N
> > print N.__version__
> >
> > We have a build slave with a very similar setup to yours (see
> > http://buildbot.scipy.org) and everything seems to be fine.
>
> It's somewhat different:
> SUSE 10.2
> Core 2 Duo 32-bit
> Kernel 2.6.18.2-34-default
> gcc version 4.1.2 20061115 (prerelease) (SUSE Linux)
> Python 2.5 (r25:51908, Nov 27 2006
> print N.__version__
> 1.0.4.dev3868
> python -c 'import numpy; numpy.test(level=1,verbosity=2)'
> [...]
> Ran 590 tests in 0.473s


Do you use Atlas? If so, did you compile it yourself or did you use a
package? There is a bug in some older 64 bit Atlas packages running on newer
intel hardware that generates illegal instruction exceptions and I am
wondering if you may have found a new 32 bit bug. One way to check this is
to multiply two big matrices together. There are many paths through Atlas,
so the known bug is not encountered in all matrix multiplications, and
perhaps not for all floating values either.

Chuck
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