Decision Optimization

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Infinite loop in CPXPratD2

  • 1.  Infinite loop in CPXPratD2

    Posted Mon January 19, 2009 07:08 PM

    Originally posted by: SystemAdmin


    [Anthony G. said:]

    Hi,

    I'm working on a project in which a branch & cut algorithm has been designed (by someone else). At each node of the tree the CPLEX callable library is used to solve a linear problem (there is only one  CPXLPptr that is updated at each node and solved). Unfortunately, for some instances there seems to be an infinite loop and the program never ends.

    I tried some debugging tools (especially ddd) to understand what could be responsible for the infinite loop. the problem occurs when CPXlpopt is called and the inifinite loop seems to be in an internal subroutine called CPXpratD2. Googling "CPXpratD2" gives no results.

    I tried both CPLEX 10.0 and 10.1.1 versions and the behaviour is exactly the same. I compiled with g++ 4.3.1 and 4.3.2, it doesn't make any difference.

    Then I tried to save the LP before it was solved by CPLEX. I used lp, mps and sav format and then tried to solve the problem via interactive CPLEX. The LP was solved instantaneously. Then I used the lpex2.c example file provided by CPLEX and tried to solve the LP with all the available methods and all converged instantaneously.

    The simplex parameters are the default ones.

    I really don't have any idea of what is responsible for such a behaviour.
    If anyone has any idea or has already experienced it, I would really appreciate feedbacks.

    Thanks in advance !

    #CPLEXOptimizers
    #DecisionOptimization


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