Re: Using OpenBLAS for Octave.app

[Andrew Janke]

On 10/21/19 7:48 PM, Marius Schamschula wrote:

>> On Oct 21, 2019, at 2:05 PM, Andrew Janke <address@hidden
>> <mailto:address@hidden>> wrote:
>>
>> Hi, Octave maintainers,
>>
>> [...snip...]
>>
> 
> I can’t say I have any more insights about the technical benefits of one
> implementation or another.
>
> However, until Apple started playing with kernel timing several macOS
> versions ago, all my octave installs used Atlas. Now Atlas is useless
> under macOS.

I didn't know about this! Is there anywhere I can read about it?

> If I recall correctly, Accelerate Framework has had some technical
> issues (i.e. erroneous results) in the past. I don’t know if these have
> been fixed.

There are some nagging test failures that happen under Apple Accelerate
but not under OpenBLAS. They have not been fixed AFAIK, nor are likely
to be.

> OpenBLAS is a variant under MacPorts, though the default variant (and
> thus the pre-compiled package) uses the Accelerate Framework.

I'm afraid Octave.app has no space for variants: our goal is to provide
a super-simple one-step drag-and-drop install for Octave on Mac. So
we're interested in deciding the Right way to do this, instead of
providing users options.

As I understand it, BLAS is actually a run-time "pluggable" thing: code
compiles against the BLAS API and not a particular implementation, and
then you can (in theory) drop in any conformant implementation library
at load & run time. But I don't know of a good mechanism for switching
between BLAS implementations, especially for a "double-click to open"
Mac GUI app like Octave.app, where you can't inherit environment
variables (like LD_PRELOAD/DYLD_INSERT_LIBRARIES) from a shell.

Cheers,
Andrew