Thomas Leveringhaus

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Recent activity by Thomas Leveringhaus Recent activity Votes
  • GRBaddconstr (or other) permissible inside of #pragma omp parallel for in C?


    Dear Gurobi-Team, is it permissible to add constraints (or anything else) to a model from the inside of a parallel for loop, like in the following (artificial) example in C? int ind[num_variants...

  • "Error: converted symmetric Q matrix has more than two billion nonzeros" despite bilinear terms with binaries


    Dear Gurobi-Team, First of all, I would like to show an excerpt from the solver log: Set parameter IntFeasTol to value 1e-06Set parameter Method to value 0Set parameter ConcurrentMethod to value 3S...

  • free malloc array after GRBupdatemodel in C?


    Dear Gurobi-team, I have a question regarding the C-API: I use malloc to allocate memory for the arrays for *cind, *cval in GRBaddconstr etc. Can I de-allocate the memory of the arrays with free() ...

  • X-Variants (size_t) of GRBaddconstrs and GRBaddvars in C-API


    Dear Gurobi-Team, do I need to use the X-Variants of the functions if I have a model with a total of more than 2 billion non-zero values, even though I do not add more than 2 billion non-zero valu...

  • Using CSC or CSR?


    Dear Gurobi-Team, I would like to ask whether it makes sense to think about the format in which sparse matrices are transferred to Gurobi? I assume, Gurobi will internally use any of the formats CS...

  • partition heuristic and threads

    Awaiting user input

    Dear Gurobi-Team, I set parameter Threads to value 64 so I got: CPU model: AMD EPYC 7502 32-Core Processor, instruction set [SSE2|AVX|AVX2]Thread count: 64 physical cores, 64 logical processors, us...

  • Concurrent Optimizer and callbacks


    Dear Gurobi-Team, I am using Concurrent Optimizer and callbacks and it seems to me, that callbacks are not called, although they should (or shouldn't?). In the reference manual (https://www.gurobi....

  • confusion about adding MVar.fromlist()


    Dear Gurobi-Team, I tried to use MVar.fromlist() ( but the given example does not work: import gurobipy as gpmodel = gp.Model(...

  • Place constraints back in the lazy constraint pool


    Dear Gurobi team, I would like to ask if it makes sense (or is even possible) to place constraints back in the lazy constraint pool. I understand how they are placed in the lazy constraint pool ini...

  • general discrete variables in gurobi


    Dear Gurobi-Team, is there any (direct) way to model general discrete variables in gurobi? What I mean are variables that take ("countable") specific integer or also specific non-integer values, e....