[jira] [Updated] (SYSTEMML-1985) Sparsity estimates of constant multiply

["Dylan Hutchison (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SYSTEMML-1985?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dylan Hutchison updated SYSTEMML-1985:
--------------------------------------
    Description: 
I've seen the following in the output of Explain recompile_hops:

{noformat}
--(505) TRead HV [327,1,1000,1000,327] [0,0,0 -> 0MB], CP
--(37959) b(*) (505,[-0.0053168...]) [327,1,1000,1000,-1] [0,0,0 -> 0MB], CP
{noformat}
 
(I altered the Explain output to show the value of the constant that HV is multiplied with, namely {{-0.0053168}})

The nnz of Hop 37959 here is 327, because multiplying a matrix by a non-zero constant does not change the non-zero structure.  But the current code marks the nnz as -1 (unknown nnz).

Let's add a check to the {{refreshSizeInformation}} of BinaryOp to handle this and related cases like division by a nonzero.  

Addition, subtraction, and mod might create zeros so they are tricky; however we can upper bound their nnz. Maybe this might be helpful in a different place?

  was:
I've seen the following in the output of Explain recompile_hops:

{noformat}
--(505) TRead HV [327,1,1000,1000,327] [0,0,0 -> 0MB], CP
--(37959) b(*) (505,[-0.0053168...]) [327,1,1000,1000,-1] [0,0,0 -> 0MB], CP
{noformat}

The nnz of Hop 37959 here is 327, because multiplying a matrix by a non-zero constant does not change the non-zero structure.  But the current code marks the nnz as -1 (unknown nnz).

Let's add a check to the {{refreshSizeInformation}} of BinaryOp to handle this and related cases like division by a nonzero.  

Addition, subtraction, and mod might create zeros so they are tricky; however we can upper bound their nnz. Maybe this might be helpful in a different place?


> Sparsity estimates of constant multiply
> ---------------------------------------
>
>                 Key: SYSTEMML-1985
>                 URL: https://issues.apache.org/jira/browse/SYSTEMML-1985
>             Project: SystemML
>          Issue Type: Improvement
>            Reporter: Dylan Hutchison
>            Priority: Minor
>
> I've seen the following in the output of Explain recompile_hops:
> {noformat}
> --(505) TRead HV [327,1,1000,1000,327] [0,0,0 -> 0MB], CP
> --(37959) b(*) (505,[-0.0053168...]) [327,1,1000,1000,-1] [0,0,0 -> 0MB], CP
> {noformat}
>  
> (I altered the Explain output to show the value of the constant that HV is multiplied with, namely {{-0.0053168}})
> The nnz of Hop 37959 here is 327, because multiplying a matrix by a non-zero constant does not change the non-zero structure.  But the current code marks the nnz as -1 (unknown nnz).
> Let's add a check to the {{refreshSizeInformation}} of BinaryOp to handle this and related cases like division by a nonzero.  
> Addition, subtraction, and mod might create zeros so they are tricky; however we can upper bound their nnz. Maybe this might be helpful in a different place?



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