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From: Eric Niebler (eric_at_[hidden])
Date: 2008-01-02 12:43:45

Sorry for the delay, the holidays were a busy time.

Jamie Allsop wrote:
> I recently had a need for some simple statistical analysis of
> performance data and thought rather than sit down and write my own
> functions for mean, variance etc. I'd take the time to learn and use the
> Accumulators library that was accepted into boost on February the 19th
> of this year,
> <>
> The only version I could find was that in the vault,
> <>
> This appears to have been updated last on 21.09.2007 03:32.
> The first thing I am wondering is why this library is not in TRUNK now
> that it is a part of boost?

The library wasn't ready for 1.35, so I never put it in trunk. Now that
we've branched for release, I can put accumulators in trunk and continue
development there.

> Secondly I thought I'd comment briefly on something that I noticed came
> up during review but has (as yet) not been addressed in the vault
> version. I too assumed that using boost::accumulators::tag::variance
> would return a useful value for variance, unfortunately it returned (in
> my case) what appeared to be an erroneous negative value. The
> 'immediate_' form worked ok.
> My comment would be that after reading the review there was some debate
> about providing a naive implementation. My thought after spending time
> reading the reviews and browsing the code to try to figure out what was
> happening was that, if I wanted a naive implementation, I could provide
> that easily myself. However I turned to the library to
> a) save me writing and maintaining the code, and
> b) to enjoy a well thought out implementation by a domain knowledgeable
> implementor.
> I therefore think that the natural choices should be accurate
> implementations. If I know enough about my data to realise I can get
> away with a naive implementation that sacrifices accuracy (perhaps for
> performance reasons) then I can select one purposefully.

Fair enough. Thanks for taking the time to give your feedback. I haven't
yet addressed this issue, but I tend to agree with you and will give
this some serious consideration.

> My first experience with the accumulators library was a mixed bag, but I
> have not used it enough to really form too many opinions on it. I
> suppose when I initially looked at it I thought I would have access to
> statistical algorithms that I could apply to my data, but in fact it
> works differently than that (and I am sure there was a good reason for
> that approach). I'll have to revisit the doc to see if I can find
> understand the motivation better. It works well as it is mind you.
> Beyond that the library appears useful and I look forward to making more
> use of it.
> I'd be very interested in seeing a newer version of the library that
> addresses the many points highlighted during the review or at least know
> that the library is currently being tidied up and will make into a boost
> release soon :)

Much of the feedback from the review has already been incorporated into
the version in the file vault. It's getting there, but slowly. I have a
day job and libraries shipping in 1.35 that needed maintenance, and
those took precedence. Sorry for the delay ... the library *will* make
its appearance in trunk soon.

Eric Niebler
Boost Consulting

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