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From "Christopher Nix (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (MATH-612) Optimisation for QRDecomposition, BiDiagonalTransformer and TriDiagonalTransformer
Date Wed, 06 Jul 2011 12:33:16 GMT

     [ https://issues.apache.org/jira/browse/MATH-612?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Christopher Nix updated MATH-612:
---------------------------------

    Attachment: TriDiagonalTransformer.patch
                BiDiagonalTransformer.patch
                QRDecompositionImpl.patch

> Optimisation for QRDecomposition, BiDiagonalTransformer and TriDiagonalTransformer
> ----------------------------------------------------------------------------------
>
>                 Key: MATH-612
>                 URL: https://issues.apache.org/jira/browse/MATH-612
>             Project: Commons Math
>          Issue Type: Improvement
>    Affects Versions: 3.0, Nightly Builds
>            Reporter: Christopher Nix
>            Priority: Minor
>              Labels: patch
>             Fix For: 3.0, Nightly Builds
>
>         Attachments: BiDiagonalTransformer.patch, QRDecompositionImpl.patch, TriDiagonalTransformer.patch
>
>
> QRDecomposition, BiDiagonalTransformer and TriDiagonalTransformer all contain methods
that create an empty matrix for population in calculations employing getEntry and setEntry
on the matrix.  Methods getEntry and setEntry perform a check to ensure the matrix indices
are in bounds.  This check is not necessary if the calling method has already ensured them
to be in bounds, for example by checking the max and min index as a looping parameter.
> Methods within QRDecomposition, BiDiagonalTransformer and TriDiagonalTransformer have
significantly improved performance over large matrices if, instead of creating an empty RealMatrix
and then using getEntry and setEntry, we create a double array for direct access and create
a RealMatrix from it at the end.

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