Number of non-integral values at each node of relaxation

Answered

Pratim Lajui

• March 07, 2021 15:29

Hello,

The log of an MIP problem displays at each node the number of variables with non-integral vales in the optimal solution of the corresponding continuous relaxation.

How could I retrieve (within a callback MIPNODE) the number of variables with non-integral vales at each node? Is there a specific option or command to retrieve this number automatically?

Thank you.

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• Official comment

  

  Simranjit Kaur

  Gurobi Staff

  • December 06, 2024 00:35

  This post is more than three years old. Some information may not be up to date. For current information, please check the Gurobi Documentation or Knowledge Base. If you need more help, please create a new post in the community forum. Or why not try our AI Gurobot?.
• 

  Jaromił Najman

  Gurobi Staff

  • March 08, 2021 18:56
  • Edited

  Hi Pratim,

  There is no direct way of obtaining the number of non-integral variable values in the node relaxation solution. However, you can use the \(\texttt{MIPNODE_REL}\) in the \(\texttt{MIPNODE}\) callback to get the node relaxation solution and check the variable solution values for integrality, see Callback Codes.

  Another, rather very alternative option would be to parse the \(\texttt{MSG_STRING}\) in a \(\texttt{MESSAGE}\) callback for the desired information.

  Best regards,
  Jaromił

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