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Gurobi's solution time far exceeds the set time.

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  • Official comment
    Gwyneth Butera
    Gurobi Staff Gurobi Staff

    Thanks for providing the log. You can see that the Gurobi solve does terminate in just about 200s:

    Explored 1 nodes (141611 simplex iterations) in 209.29 seconds (148.67 work units)

    I suspect that the "Elapsed time" also includes some pre or post processing of the model. If you could add some timestamps before and after the optimization, you might be able to arrow down where the time is being spent outside of the optimization.

  • wangyu hu
    First Comment
    First Question

    Thank you. I want to ask one more question:What does this part do? Because the previous result didn't have this, it did after adding several parameters (including: variable matrix multiplication).

    Use crossover to convert LP symmetric solution to basic solution...

    Root crossover log...

          32 DPushes remaining with DInf 0.0000000e+00                10s
           0 DPushes remaining with DInf 0.0000000e+00                10s

        1809 PPushes remaining with PInf 1.4135656e-05                10s
           1 PPushes remaining with PInf 2.6935159e-04                10s

      Push phase complete: Pinf 2.6935159e-04, Dinf 3.2534204e+02     10s

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  • Gwyneth Butera
    Gurobi Staff Gurobi Staff

    Gurobi solves your model with the barrier method. As an interior point method, the barrier does not compute a basic solution (i.e., one in a vertex of the feasible region) but an interior one, that is then pushed to the boundary (and hence transformed into a basic solution) by an additional step called crossover.

    PPushes is the number of primary push steps that remain, specifically the number of variables that must be pushed to their bounds in order to obtain a basic (vertex) solution. Likewise, DPushes is the number of dual push steps that remain.

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