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From "Phil Steitz" <phil.ste...@gmail.com>
Subject Re: Commons.Math.Distrubition
Date Sun, 07 Oct 2007 00:40:17 GMT
Can you share the data and expected results?

Phil

On 10/4/07, Amnon Lahav <amnon.lahav@gmail.com> wrote:
> sorry for the delay i just noticed the reply , i'm more then willing to
> share the code i'd love to participate in the project .
> i've tried using
> for (int i=19;i<list.size();i++){
>
> //DescriptiveStatistics commonsStat = DescriptiveStatistics.newInstance();
>
> SummaryStatistics commonsStat = SummaryStatistics.newInstance();
>
> for (int j=i-19;j<=i;j++){
>
> commonsStat.addValue(list.get(j).indicatorPrice());
>
> }
>
> Indicator indicator = new Indicator();
>
> indicator.setTime(list.get(i).indicatorTime());
>
> indicator.setValue(commonsStat.getStandardDeviation());
>
> SD.add(indicator);
>
> }
>
> ----- Original Message -----
> From: "Phil Steitz" <phil.steitz@gmail.com>
> To: "Jakarta Commons Users List" <user@commons.apache.org>
> Sent: Saturday, September 29, 2007 9:25 PM
> Subject: Re: Commons.Math.Distrubition
>
>
> > On 9/29/07, Amnon Lahav <amnon.lahav@gmail.com> wrote:
> >> Hi ,
> >> how is the Standard deviation calculated in the commons math ? because
> >> i'm
> >> getting diffrent values then my code which i used till far , iswtiched
> >> out
> >> of runtime speed considerations and i know my code is OK since it mathces
> >> the stock exchange's values ...
> >> isn't is for 20days periods  ?
> >> thanks .
> >>
> >
> > The exact computation depends on whether you supply the whole array of
> > values or feed them in one at a time; though for small arrays the
> > results should not differ.  See
> > http://commons.apache.org/math/api-1.1/org/apache/commons/math/stat/descriptive/moment/Variance.html
> > for a description of the computational formulas used.  Math.sqrt is
> > used to get the standard deviation from the variance.
> >
> > What class / method are you using?  Can you share the data and
> > expected results?  If so and you can't explain the difference, please
> > open a Jira ticket here.
> >
> > http://commons.apache.org/math/issue-tracking.html
> >
> > Phil
> >
> >>
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> >>
> >>
> >
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> >
>
>
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