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From "Phil Steitz (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MATH-631) "RegulaFalsiSolver" failure
Date Mon, 08 Aug 2011 18:24:28 GMT

    [ https://issues.apache.org/jira/browse/MATH-631?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13081104#comment-13081104
] 

Phil Steitz commented on MATH-631:
----------------------------------

I am OK removing Reg Falsi, but stand by comments above that it is a very bad idea to hack
standard algorithms and agree with Luc that maxing iterations is the correct behavior in the
case we have been discussing. It is kind of pathetic that the compromise is to drop the impl;
but in this case I don't see it as a real loss, since I can't think of any examples where
Reg Falsi would be preferable to one of the other solvers - other than for educational purposes.

> "RegulaFalsiSolver" failure
> ---------------------------
>
>                 Key: MATH-631
>                 URL: https://issues.apache.org/jira/browse/MATH-631
>             Project: Commons Math
>          Issue Type: Bug
>            Reporter: Gilles
>             Fix For: 3.0
>
>
> The following unit test:
> {code}
> @Test
> public void testBug() {
>     final UnivariateRealFunction f = new UnivariateRealFunction() {
>             @Override
>             public double value(double x) {
>                 return Math.exp(x) - Math.pow(Math.PI, 3.0);
>             }
>         };
>     UnivariateRealSolver solver = new RegulaFalsiSolver();
>     double root = solver.solve(100, f, 1, 10);
> }
> {code}
> fails with
> {noformat}
> illegal state: maximal count (100) exceeded: evaluations
> {noformat}
> Using "PegasusSolver", the answer is found after 17 evaluations.

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