RS01131: WHEN MEMORY EMPHASIS SET TO 3, CPLEX 12.4.0.1 CAN REPORT BOGUS OPTIMAL SLACK VALUES FOR ROWS THAT WERE PRESOLVED OUT.

Subscribe

You can track all active APARs for this component.

APAR status

  • Closed as fixed if next.

Error description

  • Issue involves translation of presolved optimal solution back
    to original one, combined with fact that when memory emphasis
    is turned on CPLEX doesn't factorize the optimal unpresolved
    basis for the original model.   With these settings in place,
    CPLEX 12.4.0.1 and 12.5.0.0 is likely to return
    bogus slack variables in the optimal solution for constraints
    that were presolved out of the model.
    
    RTC-13646 describes the situation internally.
    

Local fix

  • Reoptimize using the optimal basis statuses when setting
    memory emphasis on.   This will force CPLEX to refactorize
    the final basis, which fixes the problem.   That will force
    CPLEX to recompute all the values based on the factorization,
    as it does with all other settings.
    

Problem summary

  •   With numerical emphasis turned on and presolve enabled,
    slack values associated with final solution can be wrong.
    

Problem conclusion

Temporary fix

  • Fixed in 12.5. Issue was introduced in 12.4.0.1; no other
    versions have this issue.
    

Comments

APAR Information

  • APAR number

    RS01131

  • Reported component name

    ILOG CPLEX

  • Reported component ID

    5724Y4800

  • Reported release

    C30

  • Status

    CLOSED FIN

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-10-11

  • Closed date

    2013-01-02

  • Last modified date

    2013-01-02

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

Fix information

Applicable component levels

  • RC50 PSY

       UP



Rate this page:

(0 users)Average rating

Add comments

Document information


More support for:

IBM ILOG CPLEX

Software version:

C30

Reference #:

RS01131

Modified date:

2013-01-02

Translate my page

Machine Translation

Content navigation