[Numpy-discussion] Windows wheels, built, but should we deploy?

Nathaniel Smith njs at pobox.com
Fri Mar 4 23:40:29 EST 2016

On Fri, Mar 4, 2016 at 7:30 PM,  <josef.pktd at gmail.com> wrote:
> AFAIK, numpy doesn't provide access to BLAS/LAPACK. scipy does. statsmodels
> is linking to the installed BLAS/LAPACK in cython code through scipy. So far
> we haven't seen problems with different versions. I think scipy development
> works very well to isolate linalg library version specific parts from the
> user interface.

Yeah, it should be invisible to users of both numpy and scipy which
BLAS/LAPACK is in use under the hood.

> AFAIU, The main problem will be linking to inconsistent Fortran libraries in
> downstream packages that use Fortran.
> Eg. AFAIU it won't work to pip install a ATLAS based numpy and then install
> a MKL based scipy from Gohlke.

The specific scenario you describe will be a problem, but not for the
reason you state -- the problem is that (IIUC) the Gohlke scipy build
has some specific hacks where it "knows" that it can find a copy of
MKL buried at a particular location inside the numpy package (and the
Gohlke numpy build has a specific hack to put a copy of MKL there). So
the Gohlke scipy requires the Gohlke numpy, but this is due to patches
that Christoph applies to his builds.

AFAIK, outside of downstream packages that poke around the inside of
numpy like this, there should be no way for downstream packages to
know or care which BLAS/LAPACK implementation numpy is using (except
for speed, bugs, etc.).


Nathaniel J. Smith -- https://vorpus.org

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