GurobiError: Constraint has no bool value (are you trying "lb <= expr <= ub"?)

Answered

Mina Farajiamiri

September 02, 2022 09:27

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Hi, I get the following error for a constraint. 

for p in P: 
    for i in I:
        for t in T:
            if qsum(SalvageValProd[p,i,t] for i in I for t in T) <= 0.05 * scaling* qsum(delta[p,i,t] for i in I for t in T) * fprod[p]:
                SVProd[p]= qsum(SalvageValProd[p,i,t] for i in I for t in T)
            else:
                SVProd[p]= 0.05 * scaling* qsum(delta[p,i,t] for i in I for t in T) * fprod[p]

I will be very grateful if someone can help me with this error!

Mina

 

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• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  November 16, 2025 23:29

  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 try Gurobot, our chatbot interface offering instant, expert-level support.
• 

  Jaromił Najman

  • Gurobi Staff

  September 02, 2022 20:55 Edited

  Hi Mina,

  It is not possible to use modelling expressions in an \(\texttt{if}\)-clause because optimization variables have no values before the model has been optimized. Thus, you have to model this conditional statement via additional variables and constraints. The Knowledge Base article How do I model conditional statements in Gurobi? should be helpful.

  Best regards, 
  Jaromił

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• 

  Gwyneth Butera

  • Gurobi Staff

  September 02, 2022 20:00

  For additional information, please also see the Knowledge Base article: Constraint has no bool value (are you trying "lb <= expr <= ub"?)

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