Usage of variables

Answered

İrem Bahtiyar

September 29, 2021 08:59

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Hi, I have a trouble with decision variables I defined. I want to use decision variables in some mathematical context but ı get the error of "must be real number, not gurobipy.LinExpr" . The code is like that

p=[] 
for i in range(5): 
  p.append(exp((P[i]-u[i])/(0.4))

u[i]'s are decision variables, How can I solve this problem?

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• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  June 23, 2025 02:46 Edited

  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?.
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  Jaromił Najman

  • Gurobi Staff

  September 30, 2021 08:49 Edited

  Hi İrem,

  Gurobi currently does not support nonlinear expressions other than bilinear multiplication and square terms. This means that you cannot construct a term \(\exp(x)\) where \(x\) is an optimization variable.

  You can use a piecewise-linear approximation to model the \(\exp\) function. For more information, please refer to the documentation of the addGenConstrXxx functions and the documentation of general constraints.

  Best regards,
  Jaromił

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