[Numpy-discussion] Eigenvalues did not converge

Charanpal Dhanjal dhanjal@telecom-paristech...
Thu Sep 1 14:10:17 CDT 2011


As Paul suggested I'd try compiling numpy with something other than the 
BLAS/LAPACK libraries currently in use. Here is a good place to start:
http://www.scipy.org/Installing_SciPy/Linux.

Charanpal

On Thu, 1 Sep 2011 12:20:46 -0600, Rick Muller wrote:
> Yes, as I pointed out, the problem does run on the Macintosh systems.
> But Id like to be able to run these on our linux supercomputers.
> Surely this is possible, right?
>
> On Mon, Aug 29, 2011 at 9:31 AM, Paul Anton Letnes  wrote:
>
>> I recently got into trouble with these calculations (although I used
>> scipy). I actually got segfaults and "bus errors". The solution for
>> me was to not link against ATLAS, but rather link against Apples
>> blas/lapack libraries. That got everything working again. I would
>> suggest trying to install against something other than ATLAS and see
>> if that helps (or, more generally, determining which blas/lapack you
>> are linking against, and try something else).
>>
>> Paul
>>
>> On 29. aug. 2011, at 16.21, Charanpal Dhanjal wrote:
>>
>> > I posted a similar question about the non-convergence of
>> > numpy.linalg.svd a few weeks ago. Im not sure I can help but I
>> wonder
>> > if you compiled numpy with ATLAS/MKL support (try
>> numpy.show_config())
>> > and whether it made a difference? Also what is the condition
>> number and
>> > Frobenius norm of the matrix in question?
>> >
>> > Charanpal
>> >
>> > On Mon, 29 Aug 2011 08:56:31 -0600, Rick Muller wrote:
>> >> Im bumping into the old "Eigenvalues did not converge" error
>> using
>> >> numpy.linalg.eigh() on several different linux builds of numpy
>> >> (1.4.1). The matrix is 166x166. I can compute the eigenvalues on
>> a
>> >> Macintosh build of numpy, and I can confirm that there arent
>> >> degenerate eigenvalues, and that the matrix appears to be
>> negative
>> >> definite.
>> >>
>> >> Ive seen this before (though not for several years), and what I
>> >> normally do is to build lapack with -O0. This trick did not work
>> in
>> >> the current instance. Does anyone have any tricks to getting
>> eigh to
>> >> work?
>> >>
>> >> Other weird things that Ive noticed about this case: I can
>> compute
>> >> the eigenvalues using eigvals and eigvalsh, and can compute the
>> >> eigenvals/vecs using eig(). The matrix is real symmetric, and
>> Ive
>> >> tested that its symmetric enough by forcibly symmetrizing it.
>> >>
>> >> Thanks in advance for any help you can offer.
>> >
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>>
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>
> --
> Rick Muller
> rpmuller@gmail.com [6]
> 505-750-7557
>
>
>
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