[ https://issues.apache.org/jira/browse/MAHOUT-6?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12577037#action_12577037 ]
Dawid Weiss commented on MAHOUT-6: ---------------------------------- A quickie: 1. Make many, many rounds through the same code and throw away initial observations. JVMs tend to optimize code after some time (and compile it to native code of course). A single run is definitely not enough. 2. There is no HashMap on primitive types in the JDK. It's done on boxed types -- while these yield to low-level optimizations, I doubt you'll get much improvement. > Need a matrix implementation > ---------------------------- > > Key: MAHOUT-6 > URL: https://issues.apache.org/jira/browse/MAHOUT-6 > Project: Mahout > Issue Type: New Feature > Reporter: Ted Dunning > Assignee: Grant Ingersoll > Attachments: MAHOUT-6a.diff, MAHOUT-6b.diff, MAHOUT-6c.diff, > MAHOUT-6d.diff, MAHOUT-6e.diff, MAHOUT-6f.diff, MAHOUT-6g.diff, > MAHOUT-6h.patch, MAHOUT-6i.diff, MAHOUT-6j.diff, MAHOUT-6k.diff, > MAHOUT-6l.patch > > > We need matrices for Mahout. > An initial set of basic requirements includes: > a) sparse and dense support are required > b) row and column labels are important > c) serialization for hadoop use is required > d) reasonable floating point performance is required, but awesome FP is not > e) the API should be simple enough to understand > f) it should be easy to carve out sub-matrices for sending to different > reducers > g) a reasonable set of matrix operations should be supported, these should > eventually include: > simple matrix-matrix and matrix-vector and matrix-scalar linear algebra > operations, A B, A + B, A v, A + x, v + x, u + v, dot(u, v) > row and column sums > generalized level 2 and 3 BLAS primitives, alpha A B + beta C and A u + > beta v > h) easy and efficient iteration constructs, especially for sparse matrices > i) easy to extend with new implementations -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.