Decision Optimization

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  • 1.  Different obj. function value and solution using CPLEX 11.0 and 12.1

    Posted 10/14/09 02:14 AM

    Originally posted by: SystemAdmin


    [odland said:]

    I am solving a traffic assignment problem using the DEMO version of GAMS which uses CPLEX 12.1 and also solving the same problem with a comercial version using CPLEX 11.0.
    My problem is linear. Code attached.
    I get a different objective function value and solution using different versions, see below.

    --------------------------------------------------------------------------------------------------------------------

    With CPLEX 12.1 I get the result:
      S O L V E      S U M M A R Y

        MODEL  MINTB_M            OBJECTIVE  nbooth_M
        TYPE    LP                  DIRECTION  MINIMIZE
        SOLVER  CPLEX              FROM LINE  211

    **** SOLVER STATUS    1 Normal Completion       
    **** MODEL STATUS      1 Optimal                 
    [glow=red,2,300]**** OBJECTIVE VALUE                5.0000[/glow]
    RESOURCE USAGE, LIMIT          0.015      1000.000
    ITERATION COUNT, LIMIT        30        100000

    [glow=red,2,300]ILOG CPLEX      Aug 14, 2009 23.2.1 WIN 12361.12582 VIS x86/MS Windows
    Cplex 12.1.0, GAMS Link 34 [/glow]

    LP status(1): optimal
    Optimal solution found.
    Objective :          5.000000



    **** REPORT SUMMARY :        0    NONOPT
                                0 INFEASIBLE
                                0  UNBOUNDED
    GAMS Rev 232  WIN-VIS 23.2.1 x86/MS Windows            10/13/09 17:06:23 Page 11
    Nine Node Network
    E x e c u t i o n


    ----    224 VARIABLE nbooth_M.L            =      5.0000  number of toll booths
                                                              when eta is driven to
                                                              zero

    ----    224 PARAMETER report 

                toll          y

    2  .5      4.0000      1.0000
    5  .7    11.2000      1.0000
    6  .8      7.2000      1.0000
    7  .3      4.0000      1.0000
    9  .7      3.2000      1.0000
    com.                  5.0000


    ------------------------------------------------------------------------------------------------------------------

    With CPLEX 11.0 I get the result:
    S O L V E      S U M M A R Y

        MODEL  MINTB_M            OBJECTIVE  nbooth_M
        TYPE    LP                  DIRECTION  MINIMIZE
        SOLVER  CPLEX              FROM LINE  211

    **** SOLVER STATUS    1 NORMAL COMPLETION       
    **** MODEL STATUS      1 OPTIMAL                 
    [glow=red,2,300]**** OBJECTIVE VALUE                6.0000[/glow]

    RESOURCE USAGE, LIMIT          0.000      1000.000
    ITERATION COUNT, LIMIT        40        100000

    [glow=red,2,300]ILOG CPLEX    Dec 24, 2007 LNX.CP.CL 22.6 035.037.041.lx3 For Cplex 11.0
    Cplex 11.0.0, GAMS Link 34 [/glow]

    Optimal solution found.
    Objective :          6.000000



    **** REPORT SUMMARY :        0    NONOPT
                                0 INFEASIBLE
                                0  UNBOUNDED
    GAMS Rev 149  x86/Linux                                                                          10/13/09 17:09:06 Page 13
    Nine Node Network
    E x e c u t i o n


    ----    224 VARIABLE nbooth_M.L            =      6.0000  number of toll booths when eta is driven to zero

    ----    224 PARAMETER report 

                toll          y

    2  .5      4.0000      1.0000
    5  .7      9.0792      1.0000
    6  .8      7.2000      1.0000
    7  .3      6.1208      1.0000
    7  .4      2.1208      1.0000
    9  .7      1.0792      1.0000
    com.                  6.0000

    --------------------------------------------------------------------------------------------------------------------------



    #CPLEXOptimizers
    #DecisionOptimization


  • 2.  Re: Different obj. function value and solution using CPLEX 11.0 and 12.1

    Posted 10/14/09 02:23 AM

    Originally posted by: SystemAdmin


    [odland said:]

    Forgot to say that I would be very grateful if someone could help me by explaining this or telling me what I'm doing wrong! Thank you for your time!
    #CPLEXOptimizers
    #DecisionOptimization


  • 3.  Re: Different obj. function value and solution using CPLEX 11.0 and 12.1

    Posted 10/14/09 09:52 AM

    Originally posted by: SystemAdmin


    [johncui said:]

    Can you output lp or mps files in CPLEX11 and CPLEX12? And check the 2 lp files are equal or not?

    If the files are equal, and objective are not equal, could you please send your model to me?

    jcui@cn.ibm.com

    John Cui
    #CPLEXOptimizers
    #DecisionOptimization