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From "Gilles (JIRA)" <>
Subject [jira] [Commented] (MATH-815) Multivariate Normal Distribution
Date Tue, 24 Jul 2012 11:18:35 GMT


Gilles commented on MATH-815:

In the test classes:
* Please remove all the "throws Exception" clauses. There are no checked exceptions in CM.
* The "testSampling" method should probably be _defined_ in the (abstract) parent class, i.e.
once for all implementations. I think that we should probably adapt the corresponding code
in "RealDistributionAbstractTest". Maybe that it is not easy; if so, the issue should definitely
be raised on the "dev" ML.

About the API of {{MultivariateNormalDistribution}}:
* {{getColumnDimension}} should probably be simply {{getDimensions}}. And it should actually
be defined in the base class (which stores a "numDimensions" instance variable).
* To be consistent with class {{NormalDistribution}}, {{getMu}} should become {{getMean}}.
* Unless I'm mistaken, there seems to be a contradiction: the covariance matrix is called
"sigma" (instance variable and accessor method) whereas it should rather be "covariance".
* For consistency, the {{getVariances}} method should be replaced with a {{getStandardDeviation}}

In {{AbstractMultivariateRealDistribution}}:
* The usage of {{RandomData}} is deprecated (cf. MATH-823). Please store an instance of {{RandomGenerator}}
(to be initialized in the constructor).
* The "sample()" method should be "abstract" (instead of returning a useless array).
* "numDimensions" should be "private" and "final" (and initialized by the constructor).

If anything is not clear, do not hesitate to ask on the "dev" ML.

> Multivariate Normal Distribution
> --------------------------------
>                 Key: MATH-815
>                 URL:
>             Project: Commons Math
>          Issue Type: New Feature
>            Reporter: Jared Becksfort
>            Priority: Minor
>         Attachments: mvn.tgz, mvn2.tgz, patch
>   Original Estimate: 1m
>  Remaining Estimate: 1m
> I will submit a class for Multivariate Normal Distributions.  Not sure if it will allow
sampling initially.
> > Hello,
> >
> > I have implemented some classes for multivariate Normal distributions, multivariate
normal mixture models, and an expectation maximization fitting class for the mixture model.
 I would like to submit it to Apache Commons Math.  I still have some touching up to do so
that they fit the style guidelines and implement the correct interfaces.  Before I do so,
I thought I would at least ask if the developers of the project are interested in me submitting
> >
> > Thanks,
> > Jared Becksfort
> Dear Jared,
> Yes, that would be very nice to have such an addition! Remember to also include unit
tests (refer to the current ones for examples). The best would be to split a submission up
into multiple minor ones, each covering a natural submission (e.g. multivariate Normal distribution
in one submission), and create an issue as described at
> If you run into any problems, please do not hesitate to ask on this mailing list.
> Cheers, Mikkel.

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