[jira] [Closed] (SYSTEMML-1948) New rewrites for pushdown of trace/diag over binary ops

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

     [ https://issues.apache.org/jira/browse/SYSTEMML-1948?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Matthias Boehm closed SYSTEMML-1948.
------------------------------------
       Resolution: Fixed
         Assignee: Matthias Boehm
    Fix Version/s: SystemML 1.0

> New rewrites for pushdown of trace/diag over binary ops
> -------------------------------------------------------
>
>                 Key: SYSTEMML-1948
>                 URL: https://issues.apache.org/jira/browse/SYSTEMML-1948
>             Project: SystemML
>          Issue Type: Task
>            Reporter: Matthias Boehm
>            Assignee: Matthias Boehm
>            Priority: Minor
>             Fix For: SystemML 1.0
>
>
> This task aims to introduce new rewrite for pushing down trace and diag through unary and binary element-wise operations. An example, is the following expression from PPCA: {{trace(ZtZ * (t(C) %*% C))}} which should be rewritten as follows
> {code}
> trace(ZtZ * (t(C) %*% C))
> -> sum(diag(ZtZ) * diag(t(C) %*% C))
> -> sum(diag(ZtZ) * t(colSums(C^2)))
> -> colSums(C^2) %*% diag(ZtZ)
> {code}



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