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Date: Wed, 7 Sep 2011 01:28:10 +0000 (UTC)
From: =?utf-8?Q?S=C3=A9bastien_Brisard_=28JIRA=29?= <jira@apache.org>
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Subject: [jira] [Commented] (MATH-655) General framework for iterative
 algorithms
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    [ https://issues.apache.org/jira/browse/MATH-655?page=3Dcom.atlassian.j=
ira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=3D130985=
20#comment-13098520 ]=20

S=C3=A9bastien Brisard commented on MATH-655:
----------------------------------------

In the attached file {{iteration-manager.zip}} is a new version which follo=
ws Phil's suggestion to use composition instead of inheritance. We now have=
 three classes
* {{IterationManager}}: besides the methods to add/remove listeners, fire e=
vents and manage the iteration count, I've added {{shouldStop()}}, which re=
turns {{true}} if the iterations should be stopped. This method should be c=
alled by the iterative algorithm at the end of each iteration; it allows th=
e implementation of a custom stopping criterion. What do you think of this =
option (?)
* {{IterationListener}}
* {{IterationEvent}}

I should also add that I took Greg's suggestion into account, and replaced =
{{ArrayList}} by {{CopyOnWriteArrayList}}. Finally, you will see that {{Too=
ManyEvaluationsException}} is potentially thrown. In the final version of t=
hese classes, I'll define a proper {{TooManyIterationsException}}, with loc=
alized message and so on.

> 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=C3=A9bastien Brisard
>            Priority: Minor
>              Labels: algorithm, events
>         Attachments: iteration-manager.zip, iterative-algorithm.zip
>
>
> Following the thread [Monitoring iterative algorithms|http://mail-archive=
s.apache.org/mod_mbox/commons-dev/201108.mbox/%3CCAGRH7HrgcgoBA=3DjcoKovjiQ=
U=3DTjpQHnspBkOGNCu7oDdKk=3DK4w@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()}} th=
rows a {{TooManyEvaluationsException}}. If the proposed new feature is inte=
grated into CM, then a proper {{TooManyIterationsException}} should be crea=
ted, from which the former could derive.

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