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From: Brook Milligan (brook_at_[hidden])
Date: 20070507 20:19:31
Several people have commented, both publicly and privately, on the
Probability library I mentioned last week. There is now a new version
http://biology.nmsu.edu/software/probability/
that addresses most of the concerns. In what follows I will address
the salient points as I see them.
 The main documentation page now begins with a brief definition of
probability and likelihood.
 Runtime costs have now been quantified in a fairly simple manner.
The results are summarized on the main page, but indicate that there
is less than a 0.5% effect in a test involving a large fraction of
operations on these quantities. Is suspect this is well within the
noise, but input from those with greater benchmarking experience is
welcome.
 Additive operators are now provided within the log domain. This
completes the full set of arithmetic operators.
 A suggestion was made to combine this with the math toolkit (and
possibly the units) library. I hesitate to do this immediately
until it is clear that the Probability library is indeed acceptable.
It seems that the process would occur in stages: handle this one on
its own, then work on integration if that is generally a desirable
direction. This should stand on its own merits, at least initially.
 Another suggestion focused on the potential for a numerical value
type for the log domain, independent of probabilities. Clearly,
that is contained within this and such a type could be extracted out
for independent use. Had such a type existed, a portion of this
library would have been simpler. However, such a type will not
address the interconversions between probabilities and likelihoods
that form a natural part of much statistical modeling. Thus, the
higher level types incorporated here remain important, with or
without a general log domain type. For now it seems that this is an
implementation detail from the perspective of the Probability
library. If there is a strong interest in such a type, perhaps this
library could be refactored into two.. Again, I would opt for
waiting to assess the acceptability of this library and the general
level of interest in these different facets.
I appreciate the comments and welcome other ideas. I hope that more
people will look over the new version of the library and provide
feedback.
Thanks for your interest.
Cheers,
Brook
 Brook Milligan Internet: brook_at_[hidden] Department of Biology New Mexico State University Telephone: (505) 6467980 Las Cruces, New Mexico 88003 U.S.A. FAX: (505) 6465665
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