Christian Perau

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Recent activity by Christian Perau Recent activity Votes
  • Convert presolved model to original model

    Answered

    I am working with rather big models. After the presolve (during the ordering) I notice the highest peak in memory usage. Due to this peak I often have to reduce the Threads parameter and therefore ...

  • Objective value does not equal X * obj

    Answered

    Recently I encountered that (in some of my models) the variable values seem to be incorrectly stored into my data. When I try the following int i, error;double total_obj_by_hand=0, total_obj_by_gur...

  • Model infeasible after using GRBfixmodel

    Answered

    After using the GRBfixmodel function my MILP is reported to be infeasible since the upper bound of some variables that are zero in the optimal solution is set to a (small) negative value instead of...

  • Out of memory though memory is not exceeded

    Awaiting user input

    I am trying to solve a MILP using Bender's decomposition. Since there are many binary decision variables in the master, I need a lot of iterations. In the first iterations everything works just fin...

  • Modelling squared euclidean distance in objective function (C-API)

    Answered

    I want to implement the following objective function in the C-API: min (x²-1) + (y²-1) As far as I see it in the documentation I would need to reformulate the objective function to min x²-2x+1 + y²...

  • ValueError using model.addMConstr since gurobipy 11.0.0

    Answered

    Since updating to gurobipy I receive an ValueError when I try to use addMConstr if I include constraint names. Here is a minimal reproducible example: import gurobipy as gpfrom gurobipy import GRBi...

  • using cmake -H. -Bbuild fails

    Answered

    Hi, I am trying to use CMake to use gurobi in C like described in https://support.gurobi.com/hc/en-us/articles/360039499751-How-do-I-use-CMake-to-build-Gurobi-C-C-projects-. However, when I try to ...

  • Reduce memory usage of gurobipy Model

    Answered

    Hello, I am working with quite large linear models and finding myself with problems regarding memory usage. Building the model I observe a huge increase in memory consumption when I use model.addMV...

  • Gurobipy addMConstr() raises GurobiError: Name too long when passing list of names

    Answered

    I am trying to add constraints via the model.addMConstr() method. For debugging purposes I want to add names to the variables (so I can use them in e.g. a .lp file). However when I try to pass a li...