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Posted to dev@mahout.apache.org by "Dmitriy Lyubimov (JIRA)" <ji...@apache.org> on 2015/10/25 21:27:28 UTC

[jira] [Created] (MAHOUT-1781) Dense matrix view multiplication is 4x slower than non-view one

Dmitriy Lyubimov created MAHOUT-1781:
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             Summary: Dense matrix view multiplication is 4x slower than non-view one
                 Key: MAHOUT-1781
                 URL: https://issues.apache.org/jira/browse/MAHOUT-1781
             Project: Mahout
          Issue Type: Improvement
    Affects Versions: 0.11.0
            Reporter: Dmitriy Lyubimov
            Assignee: Dmitriy Lyubimov
            Priority: Critical


if mxA and mxB are two in-core DenseMatrix matrices, then 

mxA(::,::) %*% mxB(::,::) takes 4x the time of mxA %*% mxB.

possibly an issue of dot products on VectorViews vs. DenseVectors.

dot product over DenseVectors seems to not to go through aggregate() cost-optimized framework. 



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