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https://issues.apache.org/jira/browse/MAHOUT-673?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13024888#comment-13024888
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Dmitriy Lyubimov commented on MAHOUT-673:
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Ok, i am closing it. I really hoped Ted could pitch in with review, so if
anybody wants to add something in regards to this change, please post to the
list.
Thank you.
> Stochastic projection (SSVD) to use 64bit murmur hash to produce uniform
> distribution matrix elements
> -----------------------------------------------------------------------------------------------------
>
> Key: MAHOUT-673
> URL: https://issues.apache.org/jira/browse/MAHOUT-673
> Project: Mahout
> Issue Type: Improvement
> Affects Versions: 0.4
> Reporter: Dmitriy Lyubimov
> Assignee: Dmitriy Lyubimov
> Priority: Minor
> Fix For: 0.5, 0.6
>
> Attachments: MAHOUT-673-1.patch, MAHOUT-673-1.patch
>
>
> So, per earlier discussion on the list: for random matrix Omega in stochastic
> projection, let's use murmur hash to generate uniformly distributed elements
> in a closed interval (-1,+1] instead of using Random.nextGaussian().
> I am not sure if there's really compelling mathematical reason to do this but
> maybe it's just faster and more inline with practice accepted in Mahout for
> all this.
> The murmur 64bit value is already in the code. I just need to figure the
> optimal way to convert it into a uniform distribution.
> Github url for this issue tree:
> https://github.com/dlyubimov/mahout-commits/branches/MAHOUT-673, pull
> requests are welcome.
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