invalid expression to quad expr multiplication

Answered

Ahmad Ban

February 19, 2020 11:00 Edited

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I am trying to optimize a model, but it always result with an error of "invalid expression to quad expr multiplication", mentioning this line of code:

obj2= obj2 + (1 - z[k-1,i,c])  * z[k,i,c] * ((e[k,i] - Edod) / Ebat) + z[k-1,i,c] * (1 - z[k,i,c]) * ((Emax - e[k,i]) / Ebat)

 

I know that I cannot multiply 3 variables in Gurobi! But what to do in this case?

By the way, I tried to break the equation into multiple equations with 2 variables in each one of them, but the problem still available!

 

Any solution?

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• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  June 23, 2025 03:17 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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  Yuriy Zinchenko

  • Gurobi Staff

  February 20, 2020 03:54

  You can resolve this by adding auxiliary variables, for instance, if you want

  x * y * z

  term in your objective, introduce auxiliary u variable and set u == x*y through a constraint, then you can use

  u * z

  as part of your objective expression.

   

  Hope this helps.

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