Re: [ojAlgo-user] QuadraticSolver with unsatisfiable constraints

[Anders P. <an...@op...>]

On 16 nov 2009, at 11.06, Pierre AUSLAENDER wrote:

> Hello,
>
> Thank you for this library, which is a joy to use - once I got over  
> the lack of documentation.
>
> I'm using the QuadraticSolver (ActiveSetSolver) on a least squares  
> minimisation problem, under a set of linear constraints. When the  
> constraints can be satisfied, it works perfectly. However, when the  
> constraints cannot be satisfied, the solver still returns with an  
> OPTIMAL state after a few iterations. I was puzzled until I  
> discovered the QuadraticSolver.validateSolution(...) methods, which  
> I can use to effectively test the solution against the constraints.
>
> Is this the way it is supposed to work, or did I do something wrong?  
> I would have expected the solver to FAIL instead.


I recently fixed a couple of bugs related to this. Get the latest  
snapshot download from Source Forge, and try if that solves your  
problem. If it doesn't I'd like you to give me (junit) test case.


> As an aside question, there is the following JavaDoc comment on  
> ExpressionBasedModel.addConstraint(final String aName, ....): Note  
> that only the first constraint you add will be used by the solver.  
> What does this comment mean? Is it simply related to the uniqueness  
> of the constraint name, or has it wider implications?


That comment should have been removed. It was only relevant for the  
now removed/replaced KnapsckSolver. That solver could only use 1  
constraint - the first one you added. I'll correct the javadoc comment  
now.


/Anders



> Thank you,
> Pierre
>
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