[Numpy-discussion] numarray cholesky solver ?

David M. Cooke cookedm at physics.mcmaster.ca
Fri Apr 15 10:48:55 EDT 2005

Piotr Luszczek <luszczek at cs.utk.edu> writes:

> Hi all,
> the Cholesky routine that's been mentioned (dpotrs) is from LAPACK (I
> apologize if every body knows that).
> I'm on the LAPACK team right now and we were wondering if we should
> provide bindings for Python. It is almost trivial to do with Pyrex.
> But Numeric and numarray already have some functionality in it.
> Also, I don't know about popularity of PyLapack.
> So my question is if there is a need for the specialized LAPACK
> routines. And if so, which API it should use (Numeric, numarray,
> Numeric3, scipy_core, standard array, minimum standard array implementation
> or array protocol meta info).

You'll probably first want to look at scipy, which already wraps (all?
most?) of LAPACK in its scipy.linalg package (including dpotrs :-)

It uses f2py to make the process much easier.

Since you mention you're on the LAPACK team ...

I've been working on redoing the f2c'd LAPACK wrappers in Numeric,
updating them to the current version...except: what *is* the current
version? The patches on netlib are 2-3 years old, and you have to grab
them separately, file-by-file (can I say how insanely stupid that
is?). Also ... they break: with some test cases (derived from ones
posted to our bug tracker) some routines segfault.

Is it the LAPACK 3e? If that's the case, we can't use it unless there
are C versions (Numeric only requires Python and a C compiler;
throwing a F90 compiler in there is *not* an option -- we don't even
require a F77 compiler).

I ended up using the source from Debian unstable from the lapack3
package, and those work fine.

|David M. Cooke                      http://arbutus.physics.mcmaster.ca/dmc/
|cookedm at physics.mcmaster.ca

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