Eli Towle

Gurobi Staff Gurobi Staff
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Activity overview

Latest activity by Eli Towle

  • Eli Towle commented,

    1. Community
    2. Modeling
    3. How to use model.get(A) function?

    Pyomo doesn't support all of the features available in the native Gurobi Python API. However, if you're using the "persistent" Gurobi interface, you can access the underlying \(\texttt{gurobipy}\) ...

  • Eli Towle commented,

    1. Community
    2. Algorithms
    3. Getting "DUAL_INFEASIBLE" when solving a very simple linear programming problem.

    If you set the InfUnbdInfo parameter, Gurobi will supply you with an unbounded ray that proves the model is infeasible. You can query this ray by examining the UnbdRay attribute of each Var object....

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    • Eli Towle
    • Edited
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  • Eli Towle commented,

    1. Community
    2. Programming
    3. The solution returned by GUROBI is not optimal

    By default, variables added via Model.addVar() or Model.addVars() have a lower bound of \( 0 \). If the \( Z \) variables are free, you should define them as follows: Z = m.addVars(Ind, lb=-GRB.INF...

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    • Eli Towle
    • Edited
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  • Eli Towle commented,

    1. Community
    2. Feature Requests
    3. Output solutions during solve

    Here are two ways to view new incumbent solutions as Gurobi finds them: Query the new incumbent solution in a MIPSOL callback. In Python, this can be done with Model.cbGetSolution(). You might fin...

  • Eli Towle commented,

    1. Community
    2. Modeling
    3. How to show model equation from .mps file to Jupyter notebook?

    Gurobi's read() function reads the model file into a Model object. To print the content of a model file, use Python's built-in open() function: with open("Outputs/model_v1.mps", "r") as f: conte...

  • Eli Towle commented,

    1. Community
    2. Algorithms
    3. Always Global Solutions?

    Gurobi doesn't return a certificate of optimality that you can use to manually verify that the solution to your non-convex problem is optimal. You have access to the optimal solution, which can be ...

  • Eli Towle commented,

    1. Community
    2. Algorithms
    3. Always Global Solutions?

    Yes, Gurobi solves non-convex quadratic problems to global optimality, subject to the specified optimality tolerance. Gurobi solves such problems using a spatial branch-and-bound algorithm. The Non...

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    • Eli Towle
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  • Eli Towle commented,

    1. Community
    2. Programming
    3. Cannot access MIPGap attribute

    The example problem is a continuous linear problem, so it is not solved as a MIP and there is no MIPGap to report. The model status is \(\texttt{GRB.OPTIMAL}\), meaning the problem was solved to op...

  • Eli Towle commented,

    1. Community
    2. Modeling
    3. Divisor must be a constant

    It looks like you just need to set the NonConvex parameter to 2 to direct Gurobi to solve the model (which is made non-convex by the quadratic equality constraints): model.Params.NonConvex = 2 Note...

  • Eli Towle commented,

    1. Community
    2. Modeling
    3. Divisor must be a constant

    Which part of the implementation do you need help with? Your code looks okay, depending on how you defined \( \texttt{TK} \), \( \texttt{R} \), \( \texttt{A} \), and \( \texttt{E} \). For example, ...