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List:       jakarta-commons-dev
Subject:    Re: [math] [linear] immutability
From:       Ted Dunning <ted.dunning () gmail ! com>
Date:       2012-12-31 17:56:50
Message-ID: CAJwFCa1Gm4te_z--NYJHeQ1ojhF+6NohmCmrgoE=69saeYH9dw () mail ! gmail ! com
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On Mon, Dec 31, 2012 at 9:30 AM, Phil Steitz <phil.steitz@gmail.com> wrote:

> If we stick to
>
> 0) algebraic objects are immutable
> 1) algorithms defined using algebraic concepts should be implemented
> using algebraic objects
>
> ...
> 0)  Start, with Konstantin's help, by fleshing out the InPlace
> matrix / vector interface
> 1)  Integrate Mahout code as part of a wholesale refactoring of the
> linear package
> 2)  Extend use of the visitor pattern to perform mutations
> "in-place" (similar to 0) in effect)
>

Speaking as one of the main authors of the Mahout code and very occasional
contributor to CM, I doubt that integrating it directly will suit CM
needs/prejudices.

For instance, the whole sparse matrix problem where 0 x Inf => 0 instead of
NaN is probably not satisfactory for CM, but speed was considered a more
important requirement for Mahout.  Similarly, Mahout math depends on a
primitive collection implementation that generates over 200 classes from
templates.  That makes some of the sparse codes very fast, but it might
lead to some indigestion for CM.


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