[jira] Commented: (MAHOUT-497) Matrix get/set causes allocation (?!)

["Jonathan Young (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MAHOUT-497?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12907381#action_12907381 ] 

Jonathan Young commented on MAHOUT-497:
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Are you planning on creating the integer array once, by adding int[] cardinality to AbstractMatrix, or did you have another solution in mind?

> Matrix get/set causes allocation (?!)
> -------------------------------------
>
>                 Key: MAHOUT-497
>                 URL: https://issues.apache.org/jira/browse/MAHOUT-497
>             Project: Mahout
>          Issue Type: Bug
>            Reporter: Ted Dunning
>
> Matrix get and set check the array bounds.  But checking the array bounds calls size.  But size allocates a small integer
> array.
> This is evil and KILLs performance.
> The first fix is to avoid this in SGD based classifiers.  Second will be a real change to the matrix routines to avoid the allocation.

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