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From "Gilles (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MATH-655) General framework for iterative algorithms
Date Fri, 02 Sep 2011 12:52:10 GMT

    [ https://issues.apache.org/jira/browse/MATH-655?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13095952#comment-13095952
] 

Gilles commented on MATH-655:
-----------------------------

There are many families of algorithms that have iterative implementations but also share _other_
basic functionality (like the "solvers" family or the "optimizers" family). But there is no
multiple inheritance in Java; so, an implementation that would benefit from the boiler-plate
code of {{IterativeAlgorithm}} cannot inherit from it and also from something else (like a
solver base class).
A solution would be that all these families have {{IterativeAlgorithm}} as their common ancestor;
but it would have major (IMHO) drawbacks:
* An implementation detail (e.g. the fact that some root solver performs iterations) becomes
most prominent.
* Some specific implementations that could in fact be "non-iterative" would nevertheless look
like they are.

So, how did you intend to plug {{IterativeAlgorithm}} into the design?
The presence of a "protected" method like {{resetIterationCount}} means that it is to be inherited
from (i.e. the above "solution").


> General framework for iterative algorithms
> ------------------------------------------
>
>                 Key: MATH-655
>                 URL: https://issues.apache.org/jira/browse/MATH-655
>             Project: Commons Math
>          Issue Type: New Feature
>    Affects Versions: 3.0
>            Reporter: S├ębastien Brisard
>            Priority: Minor
>              Labels: algorithm, events
>         Attachments: iterative-algorithm.zip
>
>
> Following the thread [Monitoring iterative algorithms|http://mail-archives.apache.org/mod_mbox/commons-dev/201108.mbox/%3CCAGRH7HrgcgoBA=jcoKovjiQU=TjpQHnspBkOGNCu7oDdKk=K4w@mail.gmail.com%3E],
here is a first attempt at defining a general enough framework for iterative algorithms at
large. At the moment, the classes provide support for
> * maximum number of iterations
> * events handling
> ** initialization event (prior to entering the main loop),
> ** iteration event (after completion of one iteration),
> ** termination event (after termination of the main loop).
> These classes do not yet provide support for a stopping criterion.
> Some points worth to note
> * For the time being, the classes are part of the o.a.c.m.linear package.
> * For the time being, {{IterativeAlgorithm.incrementIterationCount()}} throws a {{TooManyEvaluationsException}}.
If the proposed new feature is integrated into CM, then a proper {{TooManyIterationsException}}
should be created, from which the former could derive.

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