[SciPy-Dev] Slight change in lstsq accuracy for 0.17 - expected?

[Ralf Gommers]

On Sat, Mar 12, 2016 at 6:16 AM, Matthew Brett <matthew.brett at gmail.com>
wrote:

> Hi,
>
> I just noticed that our (neuroimaging) test suite fails for scipy 0.17.0:
>
> https://travis-ci.org/matthew-brett/nipy/jobs/115471563
>
> This turns out to be due to small changes in the result of
> `scipy.linalg.lstsq` between 0.16.1 and 0.17.0 - on the same platform
> - the travis Ubuntu in this case.
>
> Is that expected?   I haven't investigated deeply, but I believe the
> 0.16.1 result (back into the depths of time) is slightly more
> accurate.  Is that possible?
>

That's very well possible, because we changed the underlying LAPACK routine
that's used:
https://github.com/scipy/scipy/blob/master/doc/release/0.17.0-notes.rst#scipy-linalg-improvements.
This PR also had some lstsq precision issues, so could be useful:
https://github.com/scipy/scipy/pull/5550

What is the accuracy difference in your case?

Ralf




>
> Thanks for any insight,
>
> Matthew
> _______________________________________________
> SciPy-Dev mailing list
> SciPy-Dev at scipy.org
> https://mail.scipy.org/mailman/listinfo/scipy-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/scipy-dev/attachments/20160313/636c9d07/attachment.html>