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

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

Matthias Boehm created SYSTEMML-2036:
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             Summary: 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


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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