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https://issues.apache.org/jira/browse/MATH-581?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13054160#comment-13054160
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Gilles commented on MATH-581:
-----------------------------
What I really meant above is that all that is needed is 2 abstract base classes
and nothing more (especially: no interface definition). Thus, "LinearOperator"
should not be there.
Concerning the code formatting:
* Some lines are misaligned.
* You should remove "meta-comments" such as
{noformat}
//@formatter:off
{noformat}
* IMHO, you should avoid using HTML entities; it makes the comment quite
unreadable:
{noformat}
* | x<sup>T</sup> · A · y -
* y<sup>T</sup> · A · x |
* ≥ ε,
{noformat}
In Javadoc, I think that we should stick to ASCII, and if explanations that
contain elaborate mathematical formulae are needed, they should go in the
separate user guide.
Additionally:
* The exception classes are missing an accessor for the "offending vector".
* It's not necessary to copy the arguments passed to the exception constructor.
* The "LocalizedFormats" message template is missing info on the offending
vectors (and maybe the operator but I think that it isn't possible, right?). We
should certainly use the "ExceptionContext" to pass on this info.
I can take care these last points.
{quote}
For testing purposes, it would be convenient indeed to have RealMatrix derive
from RealLinearOperator,
{quote}
I don't know why you need that. Anyways it is not backward-compatible and will
potentially entails quite a few other changes. Turning "RealMatrix" into an
abstract class is the way to go but it certainly needs a JIRA ticket. You are
welcome to raise the issue.
What we can do in the meantime is to make "AbstractRealMatrix" inherit from
"RealLinearOperator". Would that be OK for your purpose?
> Support for iterative linear solvers
> ------------------------------------
>
> Key: MATH-581
> URL: https://issues.apache.org/jira/browse/MATH-581
> Project: Commons Math
> Issue Type: New Feature
> Affects Versions: 3.0, Nightly Builds
> Reporter: Sébastien Brisard
> Labels: iterative, linear, solver
> Attachments: MATH-581-01.patch, linearoperator.zip
>
>
> Dear all,
> this issue has already been discussed on the forum. The idea is to implement
> the most popular linear iterative solvers (CG, SYMMLQ, etc...) in
> commons-math. The beauty of these solvers is that they do not need direct
> access to the coefficients of the matrix, only matrix-vector products are
> necessary. This is goof, as sometimes it is inetficient to store the
> coefficients of the matrix.
> So basically, before implementing the iterative solvers, we need to define an
> interface slightly more general than a matrix, namely LinearOperator, with
> only one basic operation: matrix-vector product.
> Here are a few interfaces and abstract classes that do that. Nothing fancy
> yet, I just wanted to have you advice on the implementation before I commit
> some solvers.
> I thought these classes could go in a package
> org.apache.commons.math.linearoperator, but really, I haven't got a clue...
> Best regards,
> Sebastien
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