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From "X. B. (JIRA)" <j...@apache.org>
Subject [jira] Updated: (MATH-504) LOESS interpolation & tricube fonction
Date Mon, 31 Jan 2011 15:08:33 GMT

     [ https://issues.apache.org/jira/browse/MATH-504?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

X. B. updated MATH-504:
-----------------------

    Description: 
the doc for tricube fonction used in LOESS smooth() says :

* @return <code>(1 - |x|<sup>3</sup>)<sup>3</sup></code>.
But I'dont see the absolute value for x.

Also, the "classical" tricube fonction (see http://www.itl.nist.gov/div898/handbook/pmd/section1/pmd144.htm)
seems to return 0 if abs( x )>1. 
In the code of the tricube method, It is apparently not the case...


    private static double tricube(final double x) {
        final double tmp = 1 - x * x * x;
        return tmp * tmp * tmp;
    }

  was:
the doc for tricube fonction used in LOESS smooth() says :

* @return <code>(1 - |x|<sup>3</sup>)<sup>3</sup></code>.
But I'dont see the absolute value for x.

Also, the "classical" tricube fonction (see http://www.itl.nist.gov/div898/handbook/pmd/section1/pmd144.htm)
seems to return 0 if abs(x)>1. 
In the code of the tricube method, It is apparently not the case...


    private static double tricube(final double x) {
        final double tmp = 1 - x * x * x;
        return tmp * tmp * tmp;
    }


> LOESS interpolation & tricube fonction
> --------------------------------------
>
>                 Key: MATH-504
>                 URL: https://issues.apache.org/jira/browse/MATH-504
>             Project: Commons Math
>          Issue Type: Bug
>    Affects Versions: 2.1
>         Environment: Win XP
>            Reporter: X. B.
>            Priority: Trivial
>              Labels: loess
>   Original Estimate: 1h
>  Remaining Estimate: 1h
>
> the doc for tricube fonction used in LOESS smooth() says :
> * @return <code>(1 - |x|<sup>3</sup>)<sup>3</sup></code>.
> But I'dont see the absolute value for x.
> Also, the "classical" tricube fonction (see http://www.itl.nist.gov/div898/handbook/pmd/section1/pmd144.htm)
> seems to return 0 if abs( x )>1. 
> In the code of the tricube method, It is apparently not the case...
>     private static double tricube(final double x) {
>         final double tmp = 1 - x * x * x;
>         return tmp * tmp * tmp;
>     }

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