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Date: Wed, 6 Jul 2011 12:31:16 +0000 (UTC)
From: "Christopher Nix (JIRA)" <jira@apache.org>
To: issues@commons.apache.org
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Subject: [jira] [Created] (MATH-612) Optimisation for QRDecomposition,
 BiDiagonalTransformer and TriDiagonalTransformer
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Optimisation for QRDecomposition, BiDiagonalTransformer and TriDiagonalTransformer
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                 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
             Fix For: 3.0, Nightly Builds


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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