On Fri, Dec 24, 2010 at 10:13 AM, Pavel Ryzhov <pavel.ryz...@gmail.com>wrote:

> Hi,
>
> I've implemented a Stable random generator based on Chambers-Mallows-Stuck
> method as it is described in "Handbook of computational statistics: concepts
> and methods" by James E. Gentle, Wolfgang Härdle, Yuichi Mori
>

Thanks!  Looks good after quick review.

>
> But I'm stuck on unit-testing of the generator as I don't have estimators
> of stable distribution parameters. I cannot use moments to
> approve/disapprove if the sample satisfies to the distribution
>
> Thus I've to fall back to tests with known moments:
> 1. Normal distribution (alpha = 2 and beta=0.0)
> 2. Cauchy distribution (alpha = 1 and beta=0.0)
> 3. Alpha > 1
> The alpha interval (0, 1) stays untested.
>
> The questions are:
> 1. Is it worth to include it into Commons Math?
>

Yes.


> 2. Are these unit-tests enough for acceptance?
>

What I try to do in these cases is find another implementation to compare
against of reference data somewhere.  I have not checked yet, but most
likely R has this distribution.  The reference data for most of the other
distribution comes from R.  Obviously, these tests are not definitive; but
agreement with R is a good indication that the implementation is correct.
Have a look in src/test/R.  See, for example, TDistributionTestCases.R.

Phil

>
> Pavel
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