[Numpy-discussion] NumPy's BLAS library on macOS?

[Jerry Morrison]

On Wed, Jul 7, 2021 at 10:14 PM Matti Picus <matti.picus at gmail.com> wrote:

>
> On 8/7/21 2:23 am, Jerry Morrison wrote:
> > Got it!
> >
> > *Summary:*
> > * Installing a numpy wheel (e.g. `pip install numpy==1.21.0`) uses its
> > embedded OpenBLAS on every platform that has a wheel.
> >   That OpenBLAS is always compiled with gcc/gfortran.
> >   In this case, `np.show_config()` reports `library_dirs =
> > ['/usr/local/lib']` even though there's no libblas in that directory.
> >
> > * Installing numpy from source (e.g. `pip install numpy==1.21.0
> > --no-binary numpy)` looks for BLAS & LAPACK libraries at build time as
> > influenced by the environment vars NPY_BLAS_ORDER/NPY_LAPACK_ORDER or
> > by the file ~/.numpy-site.cfg.
> >   On macOS, 'accelerate' is in the default search order after 'openblas'.
> >   On macOS < 11.3, importing numpy that's linked to Accelerate will
> > detect an Accelerate bug and raise a RuntimeError.
>
>
> That seems correct, although admittedly show_config could do a better
> job. The problem is that not every BLAS implementation provides a
> convenient method to self-report.
>

For implementations that don't self-report, could show_config detect that
it's using embedded OpenBLAS or a system Accelerate library?


>
> It might be nice to document all this somewhere more permanent, the
> docstring for show_config might be a good place to start.
>

Agreed. On the https://numpy.org/install/ installation page?
Do you want a PR? (How to get the translations?)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mail.python.org/pipermail/numpy-discussion/attachments/20210708/ab5fae37/attachment.html>