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Posted to issues@commons.apache.org by "Gilles (JIRA)" <ji...@apache.org> on 2012/07/17 00:32:34 UTC

[jira] [Resolved] (MATH-602) Inverse condition number

     [ https://issues.apache.org/jira/browse/MATH-602?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Gilles resolved MATH-602.
-------------------------

    Resolution: Implemented

Suggestion was implemented quite some time ago.
An "interesting" case (as a unit test) is still missing, but it should not require this issue to stay open.
                
> Inverse condition number
> ------------------------
>
>                 Key: MATH-602
>                 URL: https://issues.apache.org/jira/browse/MATH-602
>             Project: Commons Math
>          Issue Type: Improvement
>    Affects Versions: 2.2
>         Environment: All
>            Reporter: greg sterijevski
>            Priority: Minor
>              Labels: Condition, Inverse, Number
>             Fix For: 3.1
>
>         Attachments: svdinvcond, tstsvd
>
>   Original Estimate: 1h
>  Remaining Estimate: 1h
>
> In SingularValueDecompositionImpl, the condition number is given as the ratio of the largest singular value to the smallest singular value. While this is the correct calculation, because of concerns over rank deficiency, researchers have traditionally used the inverse of the condition number as a more stable indicator of rank deficiency.

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