Hi Dmitriy,

If it's OK with you I'd like to try implementing this decoration.

Any advice or guidance would be very much appreciated.

Raphael.

On 27 Nov, 2011, at 9:23 AM, Dmitriy Lyubimov (Commented) (JIRA) wrote:

> Dmitriy Lyubimov commented on MAHOUT-817:
> -----------------------------------------
> 
> For the column mean bruteforce approach is probably the simplest, we 'd have 
> to decorate input of A with mean subtraction.
> 
>> Add PCA options to SSVD code
>> ----------------------------
>> 
>>                Key: MAHOUT-817
>>                URL: https://issues.apache.org/jira/browse/MAHOUT-817
>>            Project: Mahout
>>         Issue Type: New Feature
>>   Affects Versions: 0.6
>>           Reporter: Dmitriy Lyubimov
>>           Assignee: Dmitriy Lyubimov
>>            Fix For: Backlog
>> 
>> 
>> It seems that a simple solution should exist to integrate PCA mean 
>> subtraction into SSVD algorithm without making it a pre-requisite step and 
>> also avoiding densifying the big input. 
>> Several approaches were suggested:
>> 1) subtract mean off B
>> 2) propagate mean vector deeper into algorithm algebraically where the data 
>> is already collapsed to smaller matrices
>> 3) --?
>> It needs some math done first . I'll take a stab at 1 and 2 but thoughts and 
>> math are welcome.
> 
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