[SciPy-User] understanding machine precision

[josef.pktd at gmail.com]

On Tue, Dec 14, 2010 at 2:29 PM, Francesc Alted <faltet at pytables.org> wrote:
> A Tuesday 14 December 2010 20:17:10 Nils Wagner escrigué:
>> Hi all,
>>
>> I am using ATLAS
>>
>> python -i try_deterministic.py
>>
>> lstsq
>> 0.0
>> 0.0
>> 0.0
>> 0.0
>> 0.0
>
> That's interesting.  Maybe Josef is using a threaded ATLAS?  I
> positively know that threading introduces variability in the order that
> the computations are done.  However, I'm not sure on why ATLAS has
> decided to use several threads for so small matrices ((100, 10)) :-/

No, I'm using an old plain ATLAS with a single CPU, but if Skipper is
getting it also with 32bit mkl, then there might still be another
Windows "feature" in play.

Since my results are identical across python session, but not within,
the results are still deterministic and cannot depend on how busy my
computer is.

Josef

>
> --
> Francesc Alted
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