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From Gilles Sadowski <>
Subject Re: [Math] BigDecimal to power
Date Fri, 21 Jan 2011 13:19:18 GMT

When proposing code, I think that you might get better attention by posting
to the "dev" ML.

> I changed the license for my code and wrote some junit tests while refactoring.
> I think there are many improvements since I originally emailed. I have not had any off
list expressions of interest and I wonder if there is yet any other interest in making this
available as part of Commons Math?

If the functionality is desired (let's wait for the others to answer this),
there would nevertheless be quite some changes needed for the code to fit in
Commons Math; a few things I noticed by glancing at the source:

* "main" methods
* access to "System.out" for printing
* not fully documented
* class names contain an underscore

> [...]
> The main reason I developed this code was that I needed to raise a BigDecimal to the
power of another BigDecimal. Dealing with all the different cases has been a challenge. Although
I'm not 100% confident I have handled every case, I'm reasonably happy with this effort.
> In terms of junit tests: where the expected result was not obvious to me and I could
think of no obvious other way to calculate it using the java core code, I have used results
returned from my methods to set expected results. This is better than nothing, but developers
of this code should be warned that test failures may be a result of original errors rather
than as a consequence of changes they have made. I wonder if there are some canonical math
compliance test data that I should use... I was thinking that I should document or use some
attribution or something to distinguish the different types of test if I got this far.
> Does anyone have any good advice for me at this stage?

It certainly would be better to compare with the results of another library.
At least, the "self-tests" should be marked as such.

I know that Perl has "Math::BigInt" and "Math::BigFloat" modules that might
be used to compute independent results.


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