Error when i run modelling (m.addconstr)
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Gurobi Staff
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Hi Ehab,
The syntax you used, is supported by the addQConstr function and is not supported by the addConstr function.
You could either use
m.addConstr( bat * int1 == netload[i], "c0" )
or
m.addQConstr( bat * int1, GRB.EQUAL, netload[i], "c0" )
Best regards,
Jaromił0 -
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Thank you for your response
i try using two syntax now but still error
but if i add term (bat+......)
m.addQConstr( bat + bat * int1, GRB.EQUAL, netload[i], "c0" )The program works ؟
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Could you post the error you get?
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The error you see has nothing to do with the syntax of the constraint you are adding. When you add the constraint
bat * int1 == netload[i]
your problem becomes infeasible. Thus, no feasible point is available after the optimization is finished. Therefore, you cannot access the X attribute of the variables. Apparently formulating this bilinear constraint as
bat + bat * int1 == netload[i]
seems to make your problem feasible.
A proper way of avoiding such errors would be to check the optimization status first after the optimization has finished. For an example of this, see, e.g., line 30 of the lp.py example.To correct my previous message, the syntax
m.addConstr( bat * int1, GRB.EQUAL, netload[i], "c0")
is also accepted by \(\texttt{gurobipy}\).
Best regards,
Jaromił0 -
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Thank you sir ,
I am grateful to youbat+bat *int1==netload[i]
But if you use this syntax, it is considered correct and does not affect optimization quality
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Both syntax options
m.addConstr(bat + bat * int1, GRB.EQUAL, netload[i], "c0")
and
m.addConstr(bat + bat * int1 == netload[i], "c0")
are correct.
The problem lies in the feasibility of your problem. When you use the
bat * int1 == netload[i]
equality, then no feasible point to your problem exists, i.e., there is no point satisfying all of your constraints at once. In case, you are interested in how to find what causes the infeasibility, you might want to have a look at the Knowledge Base article on How do I determine why my model is infeasible?
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