[Numpy-discussion] Dropping support for Accelerate/veclib?

[Matthew Brett]

Hi,

On Tue, Jun 11, 2013 at 5:17 AM, Pauli Virtanen <pav at iki.fi> wrote:
> David Cournapeau <cournape <at> gmail.com> writes:
> [clip]
>> What is the default ABI used on homebrew ? I think we should just
>> follow that, given that Apple cannot figure it out.
>
> I think for Scipy homebrew uses the Gfortran ABI:
> https://trac.macports.org/browser/trunk/dports/python/py-scipy/Portfile
>
> But that's probably the wrong thing to do, it doesn't work:
> http://trac.macports.org/ticket/36694
>
> For Octave, they have -ff2c:
> https://trac.macports.org/browser/trunk/dports/math/octave/Portfile
>
>     ***
>
> A third option (maybe the best one) could be to add an ABI check
> to numpy.distutils BLAS/LAPACK detection --- compile a small test
> program that checks SDOT/CDOTU/DDOT etc., and refuse to use the
> BLAS/LAPACK libraries if they give incorrect results. After that,
> we can also remove the sdot/cdotu wrappers.
>
> This approach is used by Octave.
>
> This leaves the problem of dealing with Fortran ABI to those in
> charge of the build environment, e.g., macports, Enthought, ...,
> who are also in the best position to pick the correct solution
> per each platform supported.
>
> AFAIK custom compiler flags can be injected via FOPT/FFLAGS/LDFLAGS,
> so doing something like
>
>     export FOPT="-ff2c"
>
> or
>
>     export LDFLAGS="-ldotwrp -lblas"
>
> works? This makes things a bit more complicated to the builder, an
> issue that can be solved with documentation, and keeping that up to
> date is easier than hardcoding stuff into numpy.distutils.

What will be the performance drop for the default OSX installer
version of numpy, if we drop Accelerate / veclib support?

Cheers,

Matthew