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https://issues.apache.org/jira/browse/MAHOUT-1746?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14599782#comment-14599782
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ASF GitHub Bot commented on MAHOUT-1746:
----------------------------------------
GitHub user dlyubimov opened a pull request:
https://github.com/apache/mahout/pull/145
Cumulative patch for MAHOUT-1746, MAHOUT-1753, MAHOUT-1754.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/dlyubimov/mahout mahout-0.10.x-ora-0615
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/mahout/pull/145.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #145
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commit 637e050ed3a52b06e2ce1f691c5dfb6a77074a43
Author: Dmitriy Lyubimov <[email protected]>
Date: 2015-06-22T18:56:38Z
First port of mu-variance-covariance functions
commit 806000a700450b7186f511486ca1ca828225abb3
Author: Dmitriy Lyubimov <[email protected]>
Date: 2015-06-23T01:03:51Z
Added distance functions
commit 526bfd626fbc398886b1b5dec37c6e2939ea7c4a
Author: Dmitriy Lyubimov <[email protected]>
Date: 2015-06-23T21:40:32Z
MAHOUT-1746: a ^ 2 to mean a * a not pow (a, 2.0)
commit 7c5576ce1536e8873c08e0e35b6fc032b278ed5d
Author: Dmitriy Lyubimov <[email protected]>
Date: 2015-06-23T22:38:28Z
un-privatizing some of new functions.
commit 9394ac997f014f3e32439cbdd4e40deb9f03d6c5
Author: Dmitriy Lyubimov <[email protected]>
Date: 2015-06-23T23:02:45Z
adding `dist` functions
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> Fix: mxA ^ 2, mxA ^ 0.5 to mean the same thing as mxA * mxA and mxA ::= sqrt _
> ------------------------------------------------------------------------------
>
> Key: MAHOUT-1746
> URL: https://issues.apache.org/jira/browse/MAHOUT-1746
> Project: Mahout
> Issue Type: Blog - New Blog Request
> Reporter: Dmitriy Lyubimov
> Assignee: Dmitriy Lyubimov
> Fix For: 0.10.2
>
>
> it so happens that in java, if x is of double type, Math.pow(x,2.0) and x * x
> produce different values approximately once in million random values.
> This is extremely annoying as it creates rounding errors, especially with
> things like euclidean distance computations, which eventually may produce
> occasional NaNs.
> This issue suggests to get special treatment on vector and matrix dsl to make
> sure identical fpu algorithms are running as follows:
> x ^ 2 <=> x * x
> x ^ 0.5 <=> sqrt(x)
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