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From Dmitriy Lyubimov <dlie...@gmail.com>
Subject Re: EigenDecomposition
Date Wed, 10 Jul 2013 21:13:37 GMT
fixed as part of MAHOUT-1281 patch now. I will push after code freeze.


On Wed, Jul 10, 2013 at 2:06 PM, Ted Dunning <ted.dunning@gmail.com> wrote:

> Please file.  Looks completely innocuous and it is good to be standard.
>
>
> On Wed, Jul 10, 2013 at 12:59 PM, Dmitriy Lyubimov <dlieu.7@gmail.com
> >wrote:
>
> > Looks like Lanczos is having the same problem and need to undo some
> > workarounds :
> >
> >     EigenDecomposition decomp = new EigenDecomposition(triDiag);
> >
> >     Matrix eigenVects = decomp.getV();
> >     Vector eigenVals = decomp.getRealEigenvalues();
> >     endTime(TimingSection.TRIDIAG_DECOMP);
> >     startTime(TimingSection.FINAL_EIGEN_CREATE);
> >     for (int row = 0; row < i; row++) {
> >       Vector realEigen = null;
> >       // the eigenvectors live as columns of V, in reverse order.  Weird
> > but true.
> >       Vector ejCol = eigenVects.viewColumn(i - row - 1);
> >       int size = Math.min(ejCol.size(), state.getBasisSize());
> >
> >
> >
> > On Wed, Jul 10, 2013 at 12:53 PM, Dmitriy Lyubimov <dlieu.7@gmail.com
> > >wrote:
> >
> > > changing line 329 of EigenDecomposition.java from
> > >
> > >         if (d.getQuick(j) < p) {
> > >
> > > to
> > >         if (d.getQuick(j) > p) {
> > >
> > >
> > > makes my MAHOUT-1281 patch work.
> > >
> > > should i keep the change? (question for Ted, i guess)
> > >
> > > thanks.
> > > -D
> > >
> > >
> > >
> > >
> > > On Wed, Jul 10, 2013 at 11:59 AM, Dmitriy Lyubimov <dlieu.7@gmail.com
> > >wrote:
> > >
> > >> It looks like values out of our ported EigenDecomposition are coming
> out
> > >> sorted in inverse order.
> > >>
> > >> Shouldn't it be the other way around?
> > >>
> > >
> > >
> >
>

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