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https://issues.apache.org/jira/browse/MATH-439?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12932232#action_12932232
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Gilles commented on MATH-439:
-----------------------------
I'm not an "interface" fanatic, meaning that everything should have its
{code}
interface Something {
// ...
}
{code}
together with a
{code}
public class SomethingImpl {
// ...
}
{code}
Especially when there is a single best way to implement the "Something".
In that sense, I find the {{UnivariateRealSolveFactory}} and its associated
{{UnivariateRealSolveFactoryImpl}} quite clumsy (the more so that the former is
not even an interface).
However, in the {{UnivariateRealSolver}} case, I find it completely appropriate
that the interface should be an exact image of the full behaviour of the
implementing classes. If not, it has no purpose from a programming design
viewpoint.
For example, in the {{optimization}} package, there is a specialized interface
for optimizers that rely on differentiability of the objective function. It
should be the same here for the {{NewtonSolver}}.
Similarly, there are also separate interfaces for scalar and vectorial
functions; so for the solvers too, we should find a design that clearly
distinguish between real solvers and complex solvers.
> Refactoring of solvers (package "analysis.solvers")
> ---------------------------------------------------
>
> Key: MATH-439
> URL: https://issues.apache.org/jira/browse/MATH-439
> Project: Commons Math
> Issue Type: Improvement
> Reporter: Gilles
> Priority: Minor
> Fix For: 3.0
>
> Attachments: AbstractUnivariateRealSolver.java
>
>
> The classes in package "analysis.solvers" could be refactored similarly to
> what was done for package {{optimization}}.
> * Replace {{MaxIterationsExceededException}} with
> {{TooManyEvaluationsException}}:
> Apart from the class {{MaxIterationsExceededException}} being deprecated,
> this approach makes it difficult to compare different algorithms: While the
> concept of iteration is algorithm-dependent, the user is probably mostly
> interested in the number of function evaluations.
> * Implement the method {{solve}} in the base class
> ({{UnivariateRealSolverImpl}}) and define an abstract method {{doSolve}} to
> be implemented in derived classes. This method would then use a new
> {{computeObjectiveFunction}} method that will take care of the counting of
> the function evaluations.
> * Remove "protected" fields (the root is unnecessary since it is returned by
> {{solve}}). Arguingly the function value is also not very useful (as we know
> what it should be), except for debugging purposes (in which case, it might
> not be a problem to call the function's {{value}} method once more).
> * Remove the tolerance setter (accuracy) and make the corresponding fields
> "final".
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