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https://issues.apache.org/jira/browse/MATH-1680?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Ruiqi Dong updated MATH-1680:
-----------------------------
Affects Version/s: 3.6.1
> BOBYQAOptimizer constructor fails to validate trust region radius parameters
> ----------------------------------------------------------------------------
>
> Key: MATH-1680
> URL: https://issues.apache.org/jira/browse/MATH-1680
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 3.6.1
> Reporter: Ruiqi Dong
> Priority: Minor
> Original Estimate: 0.5h
> Remaining Estimate: 0.5h
>
> The {{BOBYQAOptimizer}} constructor does not validate the
> {{initialTrustRegionRadius}} and {{stoppingTrustRegionRadius}} parameters,
> despite explicit documentation requirements stating these constraints must be
> enforced.
> According to the JavaDoc in the {{bobyqa}} method:
> {{* RHOBEG and RHOEND must be set to the initial and final values of a trust
> * region radius, so both must be positive with RHOEND no greater than
> * RHOBEG.}}
> However, the three-parameter constructor accepts invalid values without
> throwing any exceptions, violating the documented API contract. This issue
> may cause line 1178 to have the problem of dividing by 0.
>
> Test Case:
> @Test
> public void testConstructorParameterValidation() {
> // Should throw for negative initial radius
> assertThrows(IllegalArgumentException.class,
> () -> new BOBYQAOptimizer(5, -1.0, 0.001));
>
> // Should throw for negative stopping radius
> assertThrows(IllegalArgumentException.class,
> () -> new BOBYQAOptimizer(5, 1.0, -0.001));
>
> // Should throw when stopping radius > initial radius
> assertThrows(IllegalArgumentException.class,
> () -> new BOBYQAOptimizer(5, 0.5, 1.0));
>
> // Should throw for zero radii
> assertThrows(IllegalArgumentException.class,
> () -> new BOBYQAOptimizer(5, 0.0, 0.0));
> }
>
> Steps to Reproduce:
> // All of these should throw IllegalArgumentException but don't:
> // 1. Negative initial radius
> BOBYQAOptimizer opt1 = new BOBYQAOptimizer(5, -1.0, 0.001);
> // 2. Negative stopping radius
> BOBYQAOptimizer opt2 = new BOBYQAOptimizer(5, 1.0, -0.001);
> // 3. Stopping radius greater than initial radius
> BOBYQAOptimizer opt3 = new BOBYQAOptimizer(5, 0.5, 1.0);
> // 4. Zero radii
> BOBYQAOptimizer opt4 = new BOBYQAOptimizer(5, 0.0, 0.0);
>
>
> Proposed Fix: Add parameter validation to the constructor
> public BOBYQAOptimizer(int numberOfInterpolationPoints,
> double initialTrustRegionRadius,
> double stoppingTrustRegionRadius) {
> super(null);
>
> if (initialTrustRegionRadius <= 0) {
> throw new IllegalArgumentException(
> "Initial trust region radius must be positive: " +
> initialTrustRegionRadius);
> }
> if (stoppingTrustRegionRadius <= 0) {
> throw new IllegalArgumentException(
> "Stopping trust region radius must be positive: " +
> stoppingTrustRegionRadius);
> }
> if (stoppingTrustRegionRadius > initialTrustRegionRadius) {
> throw new IllegalArgumentException(
> "Stopping trust region radius (" + stoppingTrustRegionRadius +
> ") must not exceed initial trust region radius (" +
> initialTrustRegionRadius + ")");
> }
>
> this.numberOfInterpolationPoints = numberOfInterpolationPoints;
> this.initialTrustRegionRadius = initialTrustRegionRadius;
> this.stoppingTrustRegionRadius = stoppingTrustRegionRadius;
> }
>
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