Thomas Leveringhaus

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Activity overview

Latest activity by Thomas Leveringhaus
  • Thomas Leveringhaus commented,

    Hi Gurobot (AI-generated response), thanks for your reply. In the meantime, I have familiarized myself with the C-API in more detail and understand how CSR & CSC are used here. With regard to the P...

  • Thomas Leveringhaus commented,

    Hello Jaromił, thanks for your helpful answer. I can work with the limit on the number of variables at the moment by doing some variable eliminations myself, which I would have preferred to leave t...

  • Thomas Leveringhaus created a post,

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

    Answered

    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...

  • Thomas Leveringhaus created a post,

    Using CSC or CSR?

    Answered

    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...

  • Thomas Leveringhaus commented,

    Thank you David!

  • Thomas Leveringhaus commented,

    Hi David, thank you for your answer: Then it is a feature not a bug ;-) But that is a pity for me, because I can't save the new found solution to file during optimization. Is there a special reaso...

  • Thomas Leveringhaus commented,

    Or maybe Callbacks are called from alle ConcurrentMIP-Instances but maybe identifying "if where == GRB.Callback.MIPSOL" doesn't work properly in different instances?

  • Thomas Leveringhaus commented,

    Hi David, I have a callback-function like this (in python): def writesolution_callback(model, where):    if where == GRB.Callback.MIPSOL: [...] # processing of the solution and creation of t...

  • Thomas Leveringhaus commented,

    Hi David, I redeveloped/improved my optimization modell. In the past I saw improvements with the heuristic, but actually gurobi does not even start the heuristic although I set PartitionPlace to 31...

  • Thomas Leveringhaus created a post,

    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...