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https://issues.apache.org/jira/browse/MATH-631?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13080817#comment-13080817
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Luc Maisonobe commented on MATH-631:
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I don't understand.
When it was created, the maxIteration threshold was exactly designed for this
purpose: get out of infinite loops. It was later renamed maxEvaluation but the
purpose is still the same: don't get stuck. The reason why we get stuck is
irrelevant. This limit is simply a safety limit, not a tuning parameter that
user are expected to raise once they hit it hoping they will converge later on.
If they could raise it later, then they should set it to an appropriate value
at once. Hitting it implies computation failed. Regula falsi just like any
algorithm can fail if applied with the wrong parameters or to the wrong
function (in fact, even with a good setting of function accuracy, it fails to
converge if we require a bracket selection on the side that does not move).
Also detecting one bound is not updated is what Illinois and Pegasus are
designed to do.
So I think we should completely get rid of regula falsi and only keep the
better algorithms.
> "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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