GAMS World Forum

MIP is a difficult (NP hard) problem class and there is no guarantee that you will be able to solve a MIP of this size to global optimality in reasonable time. You can work on the formulation etc. No easy solution.

-Michael

Infeasible models are no errors (The "Cplex Error 1217: No solution exists" is an unfortunate by-product of an API call in the GAMS/Cplex link that can't be supressed, but it's fine). It's a valid state for an optimization model (besides optimal and unbounded). If you are interested in the...

What else should it be? Your data statement is m 'Calculation of vapour pressure, 1 @ eaporation temperature, 2 @ condensing temperature' /1*3/ T(m) This parameter set is assignment for the convience of vapour pressure calculation /1 272 2 316/ without the m=3. GAMS is a sparse system and assumes 0 ...

When you solve the RMINLP with BARON you get with the option you already supply compIIS the following information in the listing file: A problem may contain several independent IISs. Only one IIS will be found per run. Alternative IISs may be obtained by using different values of the CompIIS option ...

I agree that this is odd, but not necessarily impossible. Cplex has so few open nodes (~140) that finishing up on a particular node might allow Cplex to raise the dual bound significantly. You might try a different solver and see if they confirm the optimal solution (or the primal and dual bounds). ...

You misunderstood. Someone suggested MPSGE to you. You know this person. Go to him/her and get help. -Michael

Sorry, I can't help with MPSGE syntax. Never learned that. I guess someone suggested to you using MPSGE, I would go to that person to get help. -Michael

There are many compilation error. Get rid of them. The compiler error message will help you with this. For example, then first one: 201 chksam(i) = sum(j,sam(i,j)-sam(j,i)); **** $171,148 $171,148 **** 148 Dimension different - The symbol is referenced with more/less **** indices as declared **** 17...

Hi,

You are mixing GAMS and MPSGE syntax. The MPSGE syntax is inside a $onText/$offText area and ignored by the GAMS compiler. Check out the MPSGE introduction at: https://www.gams.com/latest/docs/UG_MPSGE_Intro.html.

-Michael

Hi, when I run the model I do get as you describe S O L V E S U M M A R Y MODEL m OBJECTIVE C_tot TYPE LP DIRECTION MINIMIZE SOLVER CPLEX FROM LINE 239 **** SOLVER STATUS 1 Normal Completion **** MODEL STATUS 1 Optimal **** OBJECTIVE VALUE 724.1415 The summary of the infeasiblilty status of rows and...