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From Ted Dunning <ted.dunn...@gmail.com>
Subject Re: how to run PCA from Mahout
Date Tue, 06 Sep 2011 19:35:24 GMT
Another option is to invent another kind of matrix that knows about an
offset.  Then a special method for times may give the right performance.

A third option is to do a little algebra on the PCA algorithm to propagate
the mean offset into the stochastic projection algorithm.

On Tue, Sep 6, 2011 at 7:24 PM, Ted Dunning <ted.dunning@gmail.com> wrote:

> Sure.
>
> Do the subtraction after the B = Q'A step in the random projection!
>
> On Tue, Sep 6, 2011 at 7:16 PM, Dmitriy Lyubimov <dlieu.7@gmail.com>wrote:
>
>> On Tue, Sep 6, 2011 at 12:11 PM, Ted Dunning <ted.dunning@gmail.com>
>> wrote:
>> > Note that normally subtracting anything fills in sparse matrices.
>>
>> is there a way to cope with this without changing SVD contracts?
>>
>
>

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