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From Abramov Pavel <p.abra...@rambler-co.ru>
Subject HA: Mahout svd command question
Date Thu, 22 Nov 2012 17:58:27 GMT
Hi, 

Here is step by step manual for Lanczos implementation:

https://cwiki.apache.org/MAHOUT/dimensional-reduction.html

Pavel
________________________________________
От: kuba [pawloch@interia.pl]
Отправлено: 22 ноября 2012 г. 21:34
To: user@mahout.apache.org
Тема: Mahout svd command question

Hi,

I'm new to hadoop, mahout, and language processing.
I'm trying to do LSA (Latent Semantic Analysis) in mahout.
I've made my own version of tf-idf matrix building (I know there's
seqdirectory and seq2sparse, that can do it for me, but I needed some
modifications).
I've done 'mahout svd' and I've got output, but don't know how to
interpret it.

According to books I've read SVD should return three matrices:
M = U * Epsilon * (Vt),

but 'mahout svd' return only one. I can't find any documentation. Which
one does it return, is it U ?

Do I have to transpose my tf-idf matrix and compute SVD again to get
second matrix ( V )?

Also I've found people using:
mahout cleansvd
what is it for? is there any good documentation?


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