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From Ted Dunning <>
Subject Re: [Math] Issue 348
Date Sun, 07 Mar 2010 18:42:31 GMT
Hmm... no this is not dependent on CM.  This is an example that I wrote in 3
minutes to illustrate the point.

I think the confusion is that I assumed that commons.math distributions
supported sampling.  I don't think that capability is available even now
(although a user contributed patches months ago to do that).  My example is
geared towards that.

The problem is probably mine.  I haven't been using commons math since the
Mahout project decided that it wasn't usable for our needs and I assumed
that this basic capability was available.

If distributions are viewed only as a pure function that computes the
density and cumulative distribution function, then what I say has no
utility, but then again, without sampling distributions are also much less

On Sat, Mar 6, 2010 at 3:42 PM, Gilles Sadowski <> wrote:

> I must say that I don't understand the example.
> Is it based on anything in CM?  I don't see a method "next()" anywhere...
> You say that it can't be done with an immutable super-class but nothing is
> mutable in the above (or is it precisely "next()" that is altering the
> content of the undefined "Gamma" class?).
> I don't understand why the "wrapped" variable has an overridden
> "getAlpha()"
> since it actually returns 1 and it is the first parameter passed to the
> constructor (which is what the accessor in the base class is supposed to
> return).
> All of this is quite unclear to me, so that I can't even judge what
> functionality would be useful (and how it could perhaps be achieved in some
> other way). Maybe it would make more sense if I could run a working
> example.

Ted Dunning, CTO

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