Robert Hildebrand

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3. model.Write "Unknown file type" with json

I see.  I can write it by using  m.Params.logfile = "myfile.log"

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• Robert Hildebrand
• August 31, 2022 18:37
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1. Community
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3. model.Write "Unknown file type" with json

I updated to Gurobi 9.5.2, but I am getting the same error with writing the log file: I can run  m.write("myfile.sol")m.write("myfile.lp")m.write("myfile.log") But then I get the error GurobiError:...

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• Robert Hildebrand
• August 31, 2022 18:34
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3. How to generate sensitivity analysis report in detail

Thanks!  I didn't know about this functionality.  That's very helpful.     

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• Robert Hildebrand
• November 19, 2021 14:34
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3. How to generate sensitivity analysis report in detail

A sensitivity analysis package in the GUROBI TOOLs github hub would be a fantastic thing to add!  This would make teaching introductory courses with gurobi much easier. Perhaps also a function to d...

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• Robert Hildebrand
• October 30, 2021 22:04
• 0 votes

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3. Testing cutting planes from tableau

Is there a python version of  GRBBinvRowi?  https://www.gurobi.com/documentation/7.5/refman/c_grbbinvrowi.html This is what I want to get access to.   I suppose, if not, I could the B^{-1} matrix b...

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• Robert Hildebrand
• November 19, 2020 16:47
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3. Testing cutting planes from tableau

1. Thanks.  I didn't know that you could access the presolved model.  That's exciting.   2. Then the question is, if we solve the LP relaxation, is there a way to look at the tabluea.  That is,    ...

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• Robert Hildebrand
• September 16, 2020 14:41
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3. Gurobi with python version 3.8

If you're on a windows computer, you need to execute the setup.py file using the python located in your anaconda distribution.   Here are my instructions for installing gurobi/anaconda:   Installin...

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• Robert Hildebrand
• September 11, 2020 02:09
• 1 vote

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3. When I relax a constraint, Gurobi finds a better dual bound faster. How can I use this?

  Yeah, MIPFocus =1 doesn't do anything.  The starting solution that I feed it is probably optimal. Sure, I'll try making these lazy constraints.  I'll also try a Lagrangian Relaxation to see if th...

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• Robert Hildebrand
• August 26, 2020 15:15
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3. When I relax a constraint, Gurobi finds a better dual bound faster. How can I use this?

The complicating constraints are actually flow constraints: m.addConstrs(( sum(F[e[0],e[1],j] for e in H.in_edges(i)) - sum(F[a[0],a[1],j] for a in H.out_edges(i)) == X[i,j] for i in V for j in V i...

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• Robert Hildebrand
• August 21, 2020 18:11
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3. When I relax a constraint, Gurobi finds a better dual bound faster. How can I use this?

(That last log is from the original model) I'm surprised that it gets stuck on 3.61 as the best bound that it can find.  

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• Robert Hildebrand
• August 20, 2020 21:58
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