Originally posted by: zyf2998

Hello， everyone！
When I execute my problem, an error message "CPLEX Error 5002: Q in 'id1461' is not positive semi-definite" comes out! Who can tell me how to sovle this problem? The attached file is my model.

Another question is: Does OPL supports if-else if-else or not? If does not, hot to implement the following secnario: if (i > 0) ()
else if (i < = ) ()
else （）
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

CPLEX can handle quadratic constraints only if they take (or can be converted to) the form "convex function <= constant". You have a constraint that looks like (R+R')*T <= B where R, T and B are variables (Route, Throughput, Bandwidth IIRC). The product R*T is quadratic but not convex, so CPLEX rejects the constraint. Unless you can reformulate your model to eliminate that constraint, I think you'll need to shift to a nonlinear (and in fact nonconvex) program solver.

/Paul

Mathematicians are like Frenchmen: whenever you say something to them, they translate it into their own language, and at once it is something entirely different. (Goethe)
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Originally posted by: zyf2998

Thank you very much for your reply!

Another question is: Does OPL supports if-else if-else or not? If does not, how to implement the following comparison case:
if (i > 0) ()
else if (i < 0) ()
else （）
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: zyf2998

For a problem: R * T < B(,R,T,B are variables), Can LINDO solve this problem?
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#DecisionOptimization