Originally posted by: SystemAdmin

Dear All,

I really need your help regarding a MIQCP in CPLEX. I formulated the problem and then tried to solve it in CPLEX but I am getting the following error:

"CPLEX Error 5002: Q in 'id182' is not positive semi-definite."

Is there any way to deal with this issue. I mean, if the constraints are not positive semi-definite, can we still solve the problem in CPLEX?

I really appreciate your help. If you want me to send the code, I will send it. Here are some of the constraints:

sum (t in Periods) X[t] Y[t]== sum (t in Periods) N[t];* where X[t] is a binary decision variable and Y[t] is an integer decision variable.
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Originally posted by: SystemAdmin

The model in CPLEX is attached, any help will be appreciated.
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Originally posted by: SystemAdmin

Is it OK to have this constraint in your model:

If X[i] is zero then Y[i] must be zero.
If X[i] is one then Y[i] must not be larger than 4.

If this is correct for your model you can just add

forall (t in Periods) Y[i] <= 4 * X[i];

and replace the offending constraint by

sum (t in Periods) Y[t]== sum (t in Periods) N[t];

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Originally posted by: SystemAdmin

Thank you for help. I just figured it out.
I have another question now: I have created a model in CPLEX 12.5 and want to call and solve the model from VBA in Excel, any idea?
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