Modeling trigonometric constraints

Answered

Victor Hinojosa

April 20, 2023 14:18

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Dear Comunity,

I can model the COS constraint y = cos (x) using the general constraint in Python, but I don't know if there is possible to model the following nonlinear constraint:

pl = k cos (d1 - d2)

Where pl, d1, d2 are variables, and k is a constant value.

I look forward to hearing your comments and support.

Regards,

Victor

Related to

• Trigonometric Functions

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  Maliheh Aramon

  • Gurobi Staff

  April 20, 2023 22:29

  Hi Victor, 

  You can take advantage of auxiliary variables:

  1. Define an auxiliary variable \(z\) and add the constraint \(z = d_1 - d_2\). 
  2. Define another auxiliary variable \(y\) and add the constraint \(y = \cos(x)\) using the Model.addGenConstrCos() method
  3. Add the constraint \(p_l = k y\) 

  An alternative to step 2) and 3) is to use the Model.addGenConstrPWL() method and implement \(p_l = k \cos(z)\) using supporting points for \(z\) and \(p_l\).

  Best regards,

  Maliheh

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  Victor Hinojosa

  April 21, 2023 12:33

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  Thank you so much for your message and support.

   

  Best Regards,

  Victor

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  Muhammad Dzulqarnain Firdausi

  March 10, 2025 06:23 Edited

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  Isn't it y = cos(z) ?

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