Decision Optimization

Decision Optimization

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  • 1.  Dual bound for a continuous optimization problem?

    Posted Mon December 03, 2012 11:07 PM

    Originally posted by: Matt31


    I'm currently using CPLEX to solve a (very large) linear program produced by the Reformulation Linearization Technique, within my own branch-and-bound framework. I'm solving the LP with the dual simplex algorithm. After a fixed number of iterations, I'd like to stop the solver and obtain a lower (dual) bound on my minimization problem. Of course, I can obtain the dual values via IloCplex.getDuals(), but is there a way to get just the dual objective value directly using the Java API?

    Apologies for the simple question, but I've been unable to find the answer after scouring the Java API docs and the discussion forum here.

    Thanks a lot,
    -Matt
    #CPLEXOptimizers
    #DecisionOptimization


  • 2.  Re: Dual bound for a continuous optimization problem?

    Posted Tue December 04, 2012 09:36 AM

    Originally posted by: Matt31


    A quick addendum to my question: I found a CPLEX tech note that discusses how to compute the dual objective using getDuals(), getReducedCosts(), getLB(), and getUB(). Of course, this is what I'm trying to avoid.
    http://www-01.ibm.com/support/docview.wss?uid=swg21399940

    So the question is still open: is there a Java API call to obtain the dual bound after running Dual Simplex?

    -Matt
    #CPLEXOptimizers
    #DecisionOptimization


  • 3.  Re: Dual bound for a continuous optimization problem?

    Posted Tue December 04, 2012 05:38 PM

    Originally posted by: Matt31


    It looks like calling IloCplex::getObjValue() does exactly what I want when the Simplex algorithm terminates early. That is, when using Dual simplex it returns the dual objective, and when using Primal simplex it returns the primal objective.
    -Matt
    #CPLEXOptimizers
    #DecisionOptimization


  • 4.  Re: Dual bound for a continuous optimization problem?

    Posted Wed December 05, 2012 05:28 PM

    Originally posted by: SystemAdmin


    Yes, exactly.
    #CPLEXOptimizers
    #DecisionOptimization