[jira] [Resolved] (MAHOUT-1148) QR Decomposition is too slow

["Ted Dunning (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MAHOUT-1148?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ted Dunning resolved MAHOUT-1148.
---------------------------------

    Resolution: Fixed

I committed the new QR decomposition.  This is a bit bold to do, but I think that the benefits are large enough to really make a difference.  The tests on the QR decomposition are pretty strict so the results should drop in.  The exception would be if somebody is checking the content of the QR decomposition itself rather than just its results since there are likely sign changes relative to the old implementation.

This impacts the ALS code including the implicit solvers.  I am hoping that we have good tests on those and will see any problems quickly.

I have also not run the full suite of tests.  If Jenkins bitches, I will reopen this bug and fix the issues.
                
> QR Decomposition is too slow
> ----------------------------
>
>                 Key: MAHOUT-1148
>                 URL: https://issues.apache.org/jira/browse/MAHOUT-1148
>             Project: Mahout
>          Issue Type: Bug
>            Reporter: Ted Dunning
>
> A user reported that QR decomposition is too slow.  I coded up a replacement that can be 10x faster under certain cases and the new version is also tested.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira