Variable upper bound is defined through addVars. Can we get active variables just like active constriants

Answered

Sudheer Reddy

December 04, 2023 18:27

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So for active constraints we can check as below. Then for active variables is there a way to check

if c.Slack < 1e-6:

When a variable lower bound and upper bound is defined in model

Is there any way to check active variables . A variable which hits upper bound or lower bound after the model is solved to optimality by Gurobi .
When Variable is in between lower and upper bound then I can consider as inactive variable. 

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• Attribute

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• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  November 13, 2026 01:33

  This post is more than two 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 try Gurobot, our chatbot interface offering instant, expert-level support.
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  Maliheh Aramon

  • Gurobi Staff

  December 04, 2023 19:10

  Hi, 

  If the model is an LP and your goal is to find the optimal basic solution, you can rely on the variable attribute VBasis, after the optimization is over, to identify whether a variable is basic (0), non-basic at lower bound (-1), non-basic at upper bound (-2), or super-basis (-3). Otherwise, you would need to query the variable value using the X attribute and compare it with the variable attributes LB/UB. 

  Best regards,

  Maliheh

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