[Numpy-discussion] wired error message in scipy.sparse.eigen function: Segmentation fault

Jankins andyjian430074@gmail....
Fri Feb 5 18:25:48 CST 2010


This problem keeps bothering me for days.

If you need more sample to test it, I got one more. I tested it this
morning. And the "segmentation  fault" happened at a specific place.

I guess, finally, I have to refer to the original eigenvalue algorithm or
Matlab.

Thanks.


On Fri, Feb 5, 2010 at 1:22 AM, David Cournapeau <cournape@gmail.com> wrote:

> On Thu, Jan 28, 2010 at 3:11 PM, David Cournapeau <david@silveregg.co.jp>
> wrote:
> > Jankins wrote:
> >> Yes. I am using scipy.sparse.linalg.eigen.arpack.
> >>
> >> The exact output is:
> >>
> >>
> /usr/local/lib/python2.6/dist-packages/scipy/sparse/linalg/eigen/arpack/_arpack.so
> >
> > I need the output of ldd on this file, actually, i.e the output of "ldd
> >
> /usr/local/lib/python2.6/dist-packages/scipy/sparse/linalg/eigen/arpack/_arpack.so".
> > It should output the libraries actually loaded by the OS.
> >
> >> In fact, the matrix is from a directed graph with about 18,000 nodes and
> >> 41,000 edges. Actually, this matrix is the smallest one I used.
> >
> > Is it available somewhere ? 41000 edges should make the matrix very
> > sparse. I first thought that your problem may be some buggy ATLAS, but
> > the current arpack interface (the one used by sparse.linalg.eigen) is
> > also quite buggy in my experience, though I could not reproduce it.
> > Having a matrix which consistently reproduce the bug would be very
> useful.
>
> Ok, I took a look at it, and unfortunately, it is indeed most likely
> an ATLAS problem. I get crashes when scipy is linked against Atlas
> (v3.8.3), but if I link against plain BLAS/LAPACK, I don't get any
> crash anymore (and valgrind does not complain).
>
> I will try with a recent development from atlas,
>
> cheers,
>
> David
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