Warm starting with VBasis and CBasis

Awaiting user input

Ethan Deakins

July 02, 2023 19:49

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I am working on a project where we solve a model multiple times.  In each iteration, we use another model to derive constraints and variables to be added to our "core" model.  At the end of the iteration, the constraints and variables we add are deleted.  I am trying to warm start the core model with VBasis and CBasis, however I don't see any evidence that the basis is being used.  I have logic for setting the basis status for the variables and constraints that are created that should make the warm start basis valid.  It doesn't seem the basis is being used, however.  I have also set the LPWarmStart parameter to 1.  The Gurobi output says "Setting LP warm start or start ignored."  It seems like the start basis is not being used because the solver T is the same with and without the basis start.  I am trying to find out if I am doing something wrong.

Related to

• Warm Start
• Simplex

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  Jaromił Najman

  • Gurobi Staff

  July 10, 2023 15:47

  Hi Ethan,

  Could you share a minimal reproducible example and a log snippet showing the behavior you see? In particular it would make sense to show how exactly you are setting the VBasis and CBasis attributes.

  Note that the default value of the LPWarmStart parameter is 1. Thus, setting it to 1 is ignored.

  Best regards, 
  Jaromił

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