[Pkg-scicomp-devel] Fixing atlas on debian/Ubuntu

David Cournapeau cournape at gmail.com
Thu Sep 3 06:38:36 UTC 2009


On Thu, Sep 3, 2009 at 3:31 PM, Sylvestre Ledru<sylvestre at debian.org> wrote:
> Hello,
>
> Le jeudi 03 septembre 2009 à 15:27 +0900, David Cournapeau a écrit :
>> Hi,
>>
>> I am a Numpy/Scipy developer, and we recently got a lot of trouble
>> from users of recent ubuntu and debian, because the atlas libraries
>> are broken (the SSE2 version give bogus results whenever complex
>> number are involved in 32 bits).
>>
>> Since the current debian package is near-impossible to decipher, I
>> started from scratch a package so that we could point numpy/scipy
>> users to a an ubuntu build on PPA. Now, I would like this effort to be
>> useful for "upstream" debian packagers. The packaging was done under
>> git, and the code available there:
>>
>> http://github.com/cournape/atlas-debian/tree/master
>
> Well, bad luck, you have been duplicating a on-going work ... :/
> See: http://svn.debian.org/viewsvn/pkg-scicomp/atlas/trunk/

well, not exactly :)  I saw your effort, but I spent most of my time
making sure to produce a binary without a single SSE instruction if
requested on a modern CPU, which you did not implement I believe.

While looking at your work, I was wondering how you could use
different binaries for modern CPU (i.e. the HWCAP flag mechanism). I
could not find useful information on what exactly can it be used for -
your work seems to imply that it can make the difference between
recent i7 Intel CPU and Core 2 Duo, but I could not find any
confirmation anywhere.

cheers,

David



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