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From sebb <seb...@gmail.com>
Subject Re: [Math] BigDecimal to power
Date Fri, 21 Jan 2011 13:36:19 GMT
On 21 January 2011 13:19, Gilles Sadowski <gilles@harfang.homelinux.org> wrote:
> Hello.
>
> 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

Also package names are not org.apache.commons.mathx.

There are also some @author tags which ought to be removed - credit
can be give elsewhere.
[Author tags quickly become unmanageable in code that is developed by
a community]

>> [...]
>>
>> 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.

Also, some of the test cases are very large - it's better to have lots
of smaller tests, so all errors can be found at once.

>
> Thanks,
> Gilles
>
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