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. Model and optimization status and solveStatus codes

Hi Benjamin, You might find the documentation of the Cluster REST API useful. If you are using the Gurobi Cluster Manager, the complete documentation on REST API can be accessed at Help -> REST API...

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• Maliheh Aramon
• September 08, 2022 23:01
• Edited
• 1 vote

1. Community
2. Modeling
3. Verification without DStart

Hi Alexander,  To warm start an LP in the Gurobi Optimizer using a start vector, you need to set both PStart for every variable and DStart for every constraint. I can think of two alternatives that...

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• Maliheh Aramon
• August 06, 2022 02:25
• 1 vote

1. Community
2. Algorithms
3. Relaxations executed by gurobi

Hi Ahmed,  Yes, if the quadratic expressions include at least one binary variable, the Gurobi Optimizer can be directed to state these expressions in different ways controlled by the parameter PreQ...

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• Maliheh Aramon
• August 02, 2022 02:53
• 1 vote

1. Community
2. Modeling
3. How to update value of parameter during model iteration?

Hi Tanmoy,  Do you mean your model formulation is parametrized based on a given \(p\) value? Gurobi Callbacks provide some flexibility such that you can add new lazy constraints to the model by the...

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• Maliheh Aramon
• June 28, 2022 21:01
• 1 vote

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