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From Ted Dunning <ted.dunn...@gmail.com>
Subject Re: QRDecomposition performance
Date Mon, 28 Jan 2013 16:36:33 GMT
Yeah... having to copy the matrix is a pain in the butt.

On Mon, Jan 28, 2013 at 8:13 AM, Ying Liao <yliao422@gmail.com> wrote:

> A wrapper is needed then because Commons Math takes in and outputs in
> different data structure.
>
>
> On Mon, Jan 28, 2013 at 3:14 AM, Sean Owen <srowen@gmail.com> wrote:
>
> > Is it worth simply using the Commons Math implementation?
> >
> > On Mon, Jan 28, 2013 at 8:04 AM, Sebastian Schelter <ssc@apache.org>
> > wrote:
> > > This is great news and will automatically boost the performance of all
> > > our ALS-based recommenders which are all using QRDecomposition
> > internally.
> > >
> > > On 28.01.2013 04:02, Ted Dunning wrote:
> > >> Did that.
> > >>
> > >> You are right.  The QRD in mahout is abysmally slow.  I wrote a new
> > version
> > >> on the airplane that seems to be about 10x faster and still jsut about
> > as
> > >> accurate (and vastly simpler).  I will put up some tests and a patch
> in
> > the
> > >> next week or so.
> > >
> >
>

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