[SciPy-User] scipy.sparse.linalg.lobpcg broken?

Bruce Southey bsouthey@gmail....
Wed Oct 13 15:48:28 CDT 2010


  On 10/13/2010 03:30 PM, Nico Schlömer wrote:
>> Did you use a random matrix as input? If yes, did you set the seed first,
>> so that it is testing the same matrix?
> I'm using the identity matrix, as in
>
> =========================== *snip* ===========================
> from scipy.sparse.linalg import lobpcg
> from scipy.sparse import identity
> import numpy as np
>
> n = 5
> X = np.ones( (n, 1) )
> A = identity( n )
> lobpcg( A, X, verbosityLevel = 10 )
> =========================== *snap* ===========================
>
> Bug report at<http://projects.scipy.org/scipy/ticket/1304>.
>
> Cheers,
> Nico
>
>
>
> On Wed, Oct 13, 2010 at 9:46 PM, Pauli Virtanen<pav@iki.fi>  wrote:
>> Wed, 13 Oct 2010 21:23:19 +0200, Nico Schlömer wrote:
>>>> It actually works for me:
>>> Okay, nice. I tried to run the script on another machine too, where it
>>> appears to work alright.
>> Did you use a random matrix as input? If yes, did you set the seed first,
>> so that it is testing the same matrix?
>>
>>> This exact same code fails on my own machine locally, meaning I'm
>>> probably missing some crucial dependencies (of Scipy?). Using Scipy
>>> 0.8.0 on Gentoo.
>>> Any idea what that could possibly be?
>> The LOBPCG code in Scipy is pretty self-contained. So I can't guess much
>> else than issues with BLAS or LAPACK?
>>
>> I'd maybe make a copy of lobpcg.py and put some checks in the symeig
>> routine. But this is just guessing, I don't know in detail how LOBPCG
>> works.
>>
>> --
>> Pauli Virtanen
>>
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Due to past history, I see eigenvalue related problems I suspect 
lapack/blas/altas so please check your installation these packages.

Can you please provide details on your system?
Like OS (gentoo is insufficient), 32 vs 64 bit, python version, numpy 
version, lapack/blas/altas versions etc.,
such the output from np.show_config()

Also, have you tried the dev versions of scipy?

Really you need to find someone else to confirm this.

Bruce





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