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From Andy Turner <>
Subject RE: [Math] BigDecimal to power
Date Thu, 20 Jan 2011 18:44:10 GMT

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?

I have added an entry in the wish list and created a JIRA issue (which I am watching) and
attached a zip file containing a copy of the src and tests code to it: 

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?

Best wishes,


-----Original Message-----
From: Andy Turner [] 
Sent: 16 December 2010 22:29
To: Commons Users List
Subject: RE: [Math] BigDecimal to power

Can do if the code is wanted...
From: Gary Gregory []
Sent: 16 December 2010 18:58
To: Commons Users List
Subject: Re: [Math] BigDecimal to power

For commons math you'd have to change the license to asl 2.


On Dec 16, 2010, at 9:07, "Andy Turner" <> wrote:

> Hi,
> I've implemented code for calculating a BigDecimal raised to the power of another BigDecimal
and which returns the result rounded to a specified number of decimal places. It is in the
maths package of my Generic library and can be found via the following URL:
> There are no third party dependencies. I have not fully tested the code and already after
I released I found a bug which is only updated in subversion repository. Anyway in general
the methods work and should be generally useful. I looked for code to do this two years ago
and although I expect there are other implementations, I had no luck finding any and this
week I bit the bullet.
> I have posted on a few forums today about this to try to encourage uptake.
> Maybe you have some suggestions about where it goes from here? Maybe it is something
for commons Math?
> Best wishes,
> Andy
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