Christian Perau
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Activity overview
Latest activity by Christian Perau-
Christian Perau created a post,
Warm start LP with barrier
AnsweredI am working with very large models that I solve iteratively changing some coefficients or RHS values between the iterations. Due to memory consumption I always need to construct and deconstrcut th...
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Christian Perau created a post,
Using -1 for lazy value gives wrong result
AnsweredHello, I recently integrated lazy constraints into my model. I just tried out some parametrization and especially the value for the Lazy attribute of the constraints I want to specify as such (in ...
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Christian Perau created a post,
Convert presolved model to original model
AnsweredI 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 ...
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Christian Perau created a post,
Objective value does not equal X * obj
AnsweredRecently 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...
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Christian Perau commented,
Hi Marika, thanks for the hint to FeasibilityTol. That´s seems to do the trick. Still I will try to reduce the coefficient range. Thank you very much! Best regards, Christian
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Christian Perau created a post,
Model infeasible after using GRBfixmodel
AnsweredAfter 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...
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Christian Perau commented,
After a while I found the source. I call the C-code from within python (via ctypes dll). In the corresponding anaconda environment I had gurobipy 11.0.1 installed. After installing gurobipy 11.0.3 ...
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Christian Perau commented,
Hi Riley, I don´t set the Username in the code. However, the license file seems ok and it does work the first 253 iterations. I removed all gurobi versions from my machine and installed 11.0.3 agai...
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Christian Perau commented,
Hi Riley, yes I am using first GRBfreemodel and right after GRBfreeenv to free the memory. But I also monitored it in during runtime and the total memory usage of the machine was at its peak less t...
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Christian Perau created a post,
Out of memory though memory is not exceeded
Awaiting user inputI 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...