[jira] [Closed] (SYSTEMML-2036) RemoveEmpty with selection vector updates nnz incorrectly

["Matthias Boehm (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SYSTEMML-2036?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Matthias Boehm closed SYSTEMML-2036.
------------------------------------
       Resolution: Fixed
         Assignee: Matthias Boehm
    Fix Version/s: SystemML 1.0

> RemoveEmpty with selection vector updates nnz incorrectly
> ---------------------------------------------------------
>
>                 Key: SYSTEMML-2036
>                 URL: https://issues.apache.org/jira/browse/SYSTEMML-2036
>             Project: SystemML
>          Issue Type: Bug
>            Reporter: Matthias Boehm
>            Assignee: Matthias Boehm
>             Fix For: SystemML 1.0
>
>
> Detailed sparsity checks revealed an issue with removeEmpty and selection vectors, where not all rows with non zeros are selected. Since we only copy the nnz from the input, the output meta data is wrong which can lead to incorrect sparse/dense representations and in the worst-case incorrect results (e.g., for sum(X!=0)).
> {code}
> Caused by: org.apache.sysml.runtime.DMLRuntimeException: Matrix nnz meta data was incorrect: (_mVar7023, actual=4515, expected=4514, inst=CP°rmempty°margin=rows°select=_mVar7022°target=_mVar7009°bRmEmptyBC=false°_mVar7023·MATRIX·DOUBLE)
>         at org.apache.sysml.runtime.controlprogram.ProgramBlock.checkSparsity(ProgramBlock.java:384)
>         at org.apache.sysml.runtime.controlprogram.ProgramBlock.executeSingleInstruction(ProgramBlock.java:297)
>         ... 10 more
> {code} 



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