[Numpy-discussion] Should we drop support for "one file" compilation mode?

[David Cournapeau]

On Tue, Oct 6, 2015 at 6:07 PM, Nathaniel Smith <njs at pobox.com> wrote:

> On Tue, Oct 6, 2015 at 10:00 AM, Antoine Pitrou <solipsis at pitrou.net>
> wrote:
> > On Tue, 6 Oct 2015 09:40:43 -0700
> > Nathaniel Smith <njs at pobox.com> wrote:
> >>
> >> If you need some npy_* function it'd be much better to let us know
> >> what it is and let us export it in an intentional way, instead of just
> >> relying on whatever stuff we accidentally exposed?
> >
> > Ok, we seem to be using only the complex math functions (npy_cpow and
> > friends, I could make a complete list if required).
>
> And how are you getting at them? Are you just relying the way that on
> ELF systems, if two libraries are loaded into the same address space
> then they automatically get access to each other's symbols, even if
> they aren't linked to each other? What do you do on Windows?
>

It is possible (and documented) to use any of the npy_ symbols from npymath
from outside numpy:
http://docs.scipy.org/doc/numpy-dev/reference/c-api.coremath.html#linking-against-the-core-math-library-in-an-extension

The design is not perfect (I was young and foolish :) ), but it has worked
fairly well and has been used in at least scipy since the 1.4/1.5 days IIRC
(including windows).

David


>
> > And, of course, we would also benefit from the CBLAS functions (or any
> > kind of C wrappers around them) :-)
> > https://github.com/numpy/numpy/issues/6324
>
> This is difficult to do from NumPy itself -- we don't necessarily have
> access to a full BLAS or LAPACK API -- in some configurations we fall
> back on our minimal internal implementations that just have what we
> need.
>
> There was an interesting idea that came up in some discussions here a
> few weeks ago -- we already know that we want to package up BLAS
> inside a Python package that (numpy / scipy / scikit-learn / ...) can
> depend on and assume is there to link against.
>
> Maybe this new package would also be a good place for exposing these
> wrappers?
>
> -n
>
> --
> Nathaniel J. Smith -- http://vorpus.org
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