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From Ted Dunning <>
Subject Re: [MATH] Matrix hierarchy reorganization
Date Tue, 22 Feb 2011 03:57:44 GMT
I really would love to have mahout-math have more in common with
commons math but there are likely some nasty conflicts in goals. What
mahout has needed up to now is fast evolution which has not been
possible with commons math because of the compatibility constraints
and because it is difficult to sub-class CM matrices effectively.
While our fast change rate has moderated, our need for efficient
sub-classing is still quite exigent.

The other major needs include the ability to serialize matrices
efficiently in the hadoop style and to carry around labels on rows and
sometimes columns. The serialization nearly requires a dependency on
hadoop which is probably bad for CM. We also use the functional style
of colt quite a lot which is pretty different from jama style.

Given these constraints I really don't know how much commonality is
feasible, but it would be great to pool our efforts if we can. Luc,
Gilles, Mikkel, have you looked at the Mahout matrices?  If you do I
am sure that you will see that we have left large gaps in what we
offer. We are, in fact, decreasing what we support over time since
that is often the most effective way to move forward in our quest to
improve our test coverage.

Let's do talk about where we can go from here.

On Monday, February 21, 2011, Gilles Sadowski
<> wrote:
>> [...]
>> The things we will for sure have some difficult discussions are:
>>  - dependencies
>>    (I guess Phil and myself don't like dependencies, whereas Ted and Gilles
>>     are happy with them)
> My position is probably bestth summarized as follows:
> 1. I'm against dependencies for everything concerning the "core business" of
>    Commons Math: A light-weight library of mathematical algorithms.
> 2. I'm for dependencies when avoiding them means re-inventing the wheel
>    (e.g. localization, logging).
> 3. Consistently with point 1, I'm against locking CM in self-inflicted
>    dependencies, a.o. publicizing an API that does not belong to the "core
>    business".
>> What I would like to see:
>>  - more exchanges with the Mahout community
> Are you ready to depend on their library?
>> [...]
> Best regards,
> Gilles
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