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