User cut: current node objective

[陈伟坤]

Dear all, 

       Recently, I want to add some special cuts by callback method. But I don't want to 

add user cut at every node. Instead, whether to add user cut or not depends on the node's

LP relaxation's objective. Also, I can use getNodeRel and then use the 

objective to calculate the current node's objective, but it costs much time. Can I get the current node's 

LP relaxation's objective directly by API?

       Thank you very much.

Bests, 

Weikun

[Kostja Siefen]

Hi Weikun,

You can add (globally valid) user cuts at nodes in a MIPNODE callback using addCut() and parameter PreCrush=1. Please see the documentation for further details and take a look at the callback example for your API.

getNodeRel() is the correct function to retrieve the node solution if it is available (you need to check MIPNODE_STATUS which has to be OPTIMAL).

Calculating the objective function value needs to be done by yourself but this should be very quick operation.

Kostja