Warning: At least one constraint uses '==' instead of '=' as sense

Answered

Millend Roy

• February 27, 2023 16:03

Hi,

I'm receiving the following warning:

Warning: At least one constraint uses '==' instead of '=' as sense

Can someone help me with this?

 

Thank you,

Millend.

Related to

• General Constraints
• Python
• Model Files

0

• 

  Alison Cozad

  Gurobi Staff

  • February 27, 2023 19:42
  • Edited

  Hi Millend,

  Based on your error, I suspect you are using an LP file for your model.  For LP files, equality constraints are defined using \(\texttt{=}\) rather than \(\texttt{==}\) . 
  
  For example, this LP will run fine:

  \ LP format - for model browsing. Use MPS format to capture full model detail.
  Minimize
  Subject To
   R0: x = 1
  Bounds
  End 

  However, this LP file has the wrong sense:

  \ LP format - for model browsing. Use MPS format to capture full model detail.
  Minimize
  Subject To
   R0: x == 1
  Bounds
  End 

  and will give the following error:

  Warning: At least one constraint uses '==' instead of '=' as sense.

   

  As an aside, a lot of our customers prefer writing the model using one of our APIs (python, Java, C++, C, etc.) --- I certainly do.  It helps is avoid a lot of these types of issues.  Would you be interested in learning one of our other interfaces?  If so, let me know your language preference, and I can send you some examples and our getting started guides.

  
  Also, I see that you are one of our commercial customers.  If you would like to have more comprehensive one-on-one support, you can always create a request at support.gurobi.com.

   

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