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Posted to issues@commons.apache.org by "Brent Worden (JIRA)" <ji...@apache.org> on 2008/05/07 15:38:58 UTC
[jira] Resolved: (MATH-204) BrentSolver throws
IllegalArgumentException
[ https://issues.apache.org/jira/browse/MATH-204?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Brent Worden resolved MATH-204.
-------------------------------
Resolution: Fixed
Fix Version/s: 1.3
SVN 654100. added root checks for the endpoints.
> BrentSolver throws IllegalArgumentException
> --------------------------------------------
>
> Key: MATH-204
> URL: https://issues.apache.org/jira/browse/MATH-204
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 1.2
> Environment: Win XP
> Reporter: Mick
> Assignee: Brent Worden
> Priority: Minor
> Fix For: 1.3
>
>
> I am getting this exception:
> java.lang.IllegalArgumentException: Function values at endpoints do not have different signs. Endpoints: [-100000.0,1.7976931348623157E308] Values: [0.0,-101945.04630982173]
> at org.apache.commons.math.analysis.BrentSolver.solve(BrentSolver.java:99)
> at org.apache.commons.math.analysis.BrentSolver.solve(BrentSolver.java:62)
> The exception should not be thrown with values [0.0,-101945.04630982173] because 0.0 is positive.
> According to Brent Worden, the algorithm should stop and return 0 as the root instead of throwing an exception.
> The problem comes from this method:
> public double solve(double min, double max) throws MaxIterationsExceededException,
> FunctionEvaluationException {
>
> clearResult();
> verifyInterval(min, max);
>
> double yMin = f.value(min);
> double yMax = f.value(max);
>
> // Verify bracketing
> if (yMin * yMax >= 0) {
> throw new IllegalArgumentException
> ("Function values at endpoints do not have different signs." +
> " Endpoints: [" + min + "," + max + "]" +
> " Values: [" + yMin + "," + yMax + "]");
> }
> // solve using only the first endpoint as initial guess
> return solve(min, yMin, max, yMax, min, yMin);
> }
> One way to fix it would be to add this code after the assignment of yMin and yMax:
> if (yMin ==0 || yMax == 0) {
> return 0;
> }
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