[Numpy-discussion] Use OpenBLAS for the binary releases?

[Dag Sverre Seljebotn]

On 11/20/2012 06:22 PM, David Cournapeau wrote:
> On Tue, Nov 20, 2012 at 5:03 PM, Sturla Molden <sturla at molden.no> wrote:
>> On 20.11.2012 15:38, David Cournapeau wrote:
>>
>>> I support this as well in principle for our binary release: one issue
>>> is that we don't have the infrastructure on mac to build an installer
>>> with multi-arch support, and we can't assume every mac out there has
>>> SSE 3 or 4 available.
>>
>> Perhaps we could check the CPU architecture at run-time, and then load
>> (or install) the correct extension module? OpenBLAS does have functions
>> for testing if SSE 3 or 4 are available, which we could adapt:
>
> Doing at runtime would be really hard. On windows, our installer does
> it at install time, and openblas should be pretty much the same than
> atlas there.

Is there a specific reason it *has* to happen at compile-time? I'd think 
one could do something like just shipping a lot of separate Python 
extensions which are really just the same module linked with different 
versions of the library, and then

if cpu_is_nehalem:
     import blas_nehalem as blas
elif ...

I'm asking a question about whether this would work in principle, I 
realize it would perhaps not fit that well in the current NumPy codebase.

One thing is one would want to propagate the BLAS/LAPACK to other 
extensions through a function pointer table much like the current NumPy 
C API.

Dag Sverre