[jira] [Updated] (MATH-1680) BOBYQAOptimizer constructor fails to validate trust region radius parameters

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MATH-1680?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

ASF GitHub Bot updated MATH-1680:
---------------------------------
    Labels: pull-request-available  (was: )

> 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
>          Components: legacy
>    Affects Versions: 3.6.1
>            Reporter: Ruiqi Dong
>            Priority: Minor
>              Labels: pull-request-available
>   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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