I agree with all points below. It occured to me later this AM that exposing the right
parameters meant that the implementations needed to be separate. I now agree with you
and Mark that this would be too tricky to implement correctly while presenting the
right interface to the user.
What is you opinion on the DiscreteDistribution int vs. double issue?
Phil
-----Original Message-----
From: Brent Worden [mailto:[EMAIL PROTECTED]
Sent: Wed 10/13/2004 2:08 PM
To: Jakarta Commons Developers List
Cc:
Subject: Re: [math] Questions regarding probability distributions
Here's my basis for the exponential, chi-squared, and gamma distribution
design (forgive me for reiterating some points made by others):
Exponential is separate because both the CDF and inverse CDF have closed form
computations. This provides better performance and higher accuracy than the iterative
method approximation.
Both exponential and chi-squared are separate from gamma to provide access
only to the parameters specific to each distribution.
In chi-squared case, extension could have easily been use but this would have
exposed the alpha and beta properties in chi-squared. This would allow users to
modify the properties in an uncontrolled fashion, possibly resulting in a
disfunctional distribution. Thus, encapsulation was used to hide the gamma properties
and only expose the relavent chi-squared properties.
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