[Numpy-discussion] Scipy dot

Nathaniel Smith njs@pobox....
Fri Nov 9 10:56:02 CST 2012


On Fri, Nov 9, 2012 at 4:25 PM, Gael Varoquaux
<gael.varoquaux@normalesup.org> wrote:
> On Fri, Nov 09, 2012 at 03:12:42PM +0000, Nathaniel Smith wrote:
>> But what if someone compiles numpy against an optimized blas (mkl,
>> say) and then compiles SciPy against the reference blas? What do you
>> do then!? ;-)
>
> This could happen. But the converse happens very often. What happens is
> that users (eg on shared computing resource) ask for a scientific python
> environment. The administrator than installs the package starting from
> the most basic one, to the most advanced one, thus starting with numpy
> that can very well build without any external blas. When he gets to scipy
> he hits the problem that the build system does not detect properly the
> blas, and he solves that problem.
>
> Also, it used to be that on the major linux distributions, numpy would not
> be build with an optimize lapack because numpy was in the 'base' set of
> packages, but not lapack. On the contrary, scipy being in the 'contrib'
> set, it could depend on lapack. I just checked, and this has been fixed
> in the major distributions (Fedora, Debian, Ubuntu).
>
> Now we can discuss with such problems should not happen, and put the
> blame on the users/administrators, the fact is that they happen often. I
> keep seeing environments in which np.linalg is unreasonnably slow.

If this is something that's been a problem for you, maybe we should
start another thread on things we could do to fix it directly? Improve
build instructions, advertise build systems that set up the whole
environment (and thus do the right thing), make numpy's setup.py
scream and yell if blas isn't available...?

-n


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