Jonasz Staszek

1. Community
2. Systems
3. Gurobi ImportError in python 3.8: undefined symbol: PyDescr_IsData

Hi, is there any particular reason you load Gurobi by from .gurobipy import * ? Normally one would expect to load it like this: from gurobipy import * If this doesn't help, please let us know, addi...

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• Jonasz Staszek
• September 28, 2023 13:52
• 1 vote

1. Community
2. Modeling
3. Available algorithm for obtaining a convex hull for 2D points

Hi Sanket, Generally speaking, Porta and Polymake can guide you towards finding strong, potentially facet-defining inequalities for your problem. The best way you could benefit from using Porta or ...

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• Jonasz Staszek
• September 19, 2023 12:43
• 1 vote

1. Community
2. Modeling
3. Available algorithm for obtaining a convex hull for 2D points

Dear Sanket, you should turn to some other software package, e.g. Porta or Polymake to perform polyhedral analysis (i.e. to get a description of the convex hull you look for) As far as I know the t...

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• Jonasz Staszek
• September 19, 2023 10:14
• 1 vote

1. Community
2. Programming
3. Infeasible solution on Gurobi/Python Model (Scheduling Model Mixed Integer Programming)

Hi Burcu, adding some meaningful names to your constraints. the documentation of the addConstrs() method mentions the 'name' parameter, which you can use to give your constraints a name. The same...

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• Jonasz Staszek
• May 03, 2023 08:42
• 1 vote

1. Community
2. Programming
3. Python quicksum() versus sum()

Hi Nan, Does this mean that building the model becomes faster if you use quicksum() or does also solving the model becomes faster when you use quicksum()? In principle, one can hope that building...

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• Jonasz Staszek
• March 23, 2023 11:51
• 1 vote

1. Community
2. Algorithms
3. Solver gets stuck in Root simplex log...

Hi Patrick, without knowledge about the model itself, I cannot give you specific guidance. Nonetheless some things I would try come below: 1) Update Gurobi to v10 - you seem to be using v. 9.5.1. 2...

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• Jonasz Staszek
• March 09, 2023 12:35
• Edited
• 1 vote

1. Community
2. Algorithms
3. Check heuristics for each solution

Hi Ana, technically applying your heuristic and function could be done from within a callback every time you get a feasible solution. But since the solver has no clue about the other function which...

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• Jonasz Staszek
• February 10, 2023 08:59
• Edited
• 1 vote

1. Community
2. Modeling
3. Save Julia Gurobi model and load and run with different datainputs

Hi Katinka, I'm no expert in Julia, but perhaps it is possible to export a module (in particular I mean to export the methods which you use to generate the model, then load them someplace else and ...

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• Jonasz Staszek
• October 28, 2022 13:32
• 1 vote

1. Community
2. Modeling
3. Optimal solution seems to ignore constraints

I want it to make sure the line return model.batteryLevel[t] == model.batteryLevel[t-1]+model.batteryCharge[t-1]-model.batteryDischarge[t-1] is checked for every t in my model, with the exception ...

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• Jonasz Staszek
• October 20, 2022 15:09
• 1 vote

1. Community
2. Modeling
3. Optimal solution seems to ignore constraints

Hi Maximilian, How your constraints are encoded results in only the first line after the function definition is executed. You can read more about the return statement here. For example, whenever th...

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• Jonasz Staszek
• October 20, 2022 12:39
• 1 vote