Maliheh Aramon

1. Community
2. Modeling
3. Minimizing the divergence of a product mix and a demand vector according to a given div-dictionary

Hi Maik,    Copying your snippet in Python gives me a different error message:  gurobipy.GurobiError: Variable has not yet been added to the model   The reason is that the sum is over \(\texttt{di...

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• Maliheh Aramon
• October 05, 2021 01:22
• 2 votes

1. Community
2. Programming
3. Cannot display log in Matlab (macos)

Hi Wei, I just tested this by running the example problem \(\texttt{mip1.m}\) in MATLAB R2021b on macOS and I was able to save the log file. I explicitly set the \(\texttt{params.logfile}\). Do you...

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• Maliheh Aramon
• June 18, 2022 14:43
• 1 vote

1. Community
2. Modeling
3. Newman iteration foamalation

Hi Kim, Your code is a bit complicated and I cannot read through it easily. As far as I understand, you are trying to implement the following mathematical model: Notation \(G = (V, E)\): A graph ...

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• Maliheh Aramon
• June 18, 2022 14:40
• 1 vote

1. Community
2. Modeling
3. Seemingly unlogical result

Hi Jochem, One possible idea to debug this behaviour is to solve the first model with the optimal solution of the second model. Given your explanation, the first model should result in infeasibilit...

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• Maliheh Aramon
• May 31, 2022 02:52
• 1 vote

1. Community
2. Algorithms
3. Change solution strategy to standard (ImproveStartGap,ImproveStartNodes,ImproveStartTime)

Hi Ilya,  The parameters ImproveStartGap, ImproveStartNodes, and ImproveStartTime trigger solution improvement strategies where the Gurobi Optimizer only focuses on improving the incumbent to find ...

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• Maliheh Aramon
• April 21, 2022 01:51
• 1 vote

1. Community
2. Programming
3. Find the variable values for different solutions by PoolSolutions

Hi Ahmad,  After setting the parameter SolutionNumber to the \(i\)-th best solution, the value of each variable can be accessed by querying the attribute Xn and not X (this attribute always reports...

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• Maliheh Aramon
• April 20, 2022 21:18
• 1 vote

1. Community
2. Programming
3. How to multiply two binary gurobi variables using Java?

Hi Hadi,    You can define a Gurobi quadratic expression object (GRBQuadExpr) and iterate through the terms in the GRBLinExpr object already defined and multiply each term by the binary variable \(...

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• Maliheh Aramon
• February 17, 2022 05:52
• 1 vote

1. Community
2. Modeling
3. Does assignment order matter?

  Hi Taylor,    Problem constraints define the feasible search space and the order by which you implement them does not matter.    The two implementation above are the same. Can you please elaborat...

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• Maliheh Aramon
• February 17, 2022 05:50
• 1 vote

1. Community
2. Programming
3. Set ObjBound

Hi Jose,   No, you cannot. The Var.setAttr() method sets the value of a variable attribute. The GRB.Callback.MIPSOL_OBJBND is not an attribute of a Var object. It is a piece of information that can...

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• Maliheh Aramon
• February 08, 2022 04:07
• 1 vote

1. Community
2. Modeling
3. How can I normalize a variable?

Hi WI,  You need a few changes. Please see below. import gurobipy as gpfrom gurobipy import GRBfrom math import sqrtif __name__ == "__main__": model = gp.Model("name") Var = model.addV...

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• Maliheh Aramon
• January 29, 2022 03:55
• Edited
• 1 vote