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how to solve numerical issues

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建城 张
  • Gurobi-versary
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how to solve the problem？Model contains large objective coefficients.  Consider reformulating model or setting NumericFocus parameter  to avoid numerical issues.

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  • Official comment
    Simranjit Kaur
    • Gurobi Staff
    This post is more than two years old. Some information may not be up to date. For current information, please check the Gurobi Documentation or Knowledge Base. If you need more help, please create a new post in the community forum, or try Gurobot, our chatbot interface offering instant, expert-level support.
  • Riley Clement
    • Gurobi Staff

    Hi 建城 张,

    Maliheh has given a very detailed answer to this question when it was asked previously: https://support.gurobi.com/hc/en-us/community/posts/4676253771025-Large-matrix-coefficients-and-large-RHS-warning

    Also, the section of our reference manual Does my model have numerical issues? and the pages that follow it will be useful reading.

    - Riley

    -1
  • 建城 张
    • Gurobi-versary
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    • First Question

    hi Riley:

    So happy that u reply me soon. i had read the article u shown me above.but unfortnately,i had try the solving ways the article given and it didnt works. could u please give me some detailed solving answer.i will appreciate it .the detailed error are shown below

    Gurobi Optimizer version 11.0.0 build v11.0.0rc2 (win64 - Windows 10.0 (19045.2))

    CPU model: AMD Ryzen 5 4500U with Radeon Graphics, instruction set [SSE2|AVX|AVX2]
    Thread count: 6 physical cores, 6 logical processors, using up to 6 threads

    Optimize a model with 724 rows, 724 columns and 1445 nonzeros
    Model fingerprint: 0x5ee04fa0
    Variable types: 0 continuous, 724 integer (724 binary)
    Coefficient statistics:
      Matrix range     [1e+00, 1e+00]
      Objective range  [6e+02, 1e+10]
      Bounds range     [1e+00, 1e+00]
      RHS range        [1e+00, 1e+00]
    Warning: Model contains large objective coefficients
             Consider reformulating model or setting NumericFocus parameter
             to avoid numerical issues.
    Found heuristic solution: objective 2.187660e+08

    Explored 0 nodes (0 simplex iterations) in 0.00 seconds (0.00 work units)
    Thread count was 1 (of 6 available processors)

    Solution count 1: 2.18766e+08

    Optimal solution found (tolerance 1.00e-04)
    Best objective 2.187660000000e+08, best bound 2.187660000000e+08, gap 0.0000%

    your sincerely

    -zhang

    0
  • Riley Clement
    • Gurobi Staff

    Hi Zhang,

    The log indicates that the solver is finding an optimal solution very quickly - almost no time at all. I would not worry about the warning for this model.

    - Riley

    0
  • 建城 张
    • Gurobi-versary
    • First Comment
    • First Question

    hi Riley，

    words can not express how  grateful i am to u。i try to optimize my model now and i hope the work will

    pay off. if u have any suggestions or improved guidence to my codes or my model.please tell me asap.i will appreciate it.hope u have a good day. best wish for u. my bro. 

    yours sincerely

    -zhang

    1

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