Hello, I am currently using CPLEX with Pyomo to solve an optimization problem but am running into issues. When I use CPLEX, I get the following results:

Problem:

- Lower bound: -inf

Upper bound: inf

Number of objectives: 1

Number of constraints: 0

Number of variables: None

Number of nonzeros: None

Sense: unknown

Solver:

- Status: ok

Termination condition: unknown

Error rc: 0

Time: 0.018349170684814453

When I run the exact same problem using CBC, I get the correct feasible solution and the following output:

Problem:

- Name: unknown

Lower bound: 7769610119.0

Upper bound: 7769610119.0

Number of objectives: 1

Number of constraints: 70081

Number of variables: 61328

Number of nonzeros: 56656

Sense: minimize

Solver:

- Status: ok

User time: -1.0

System time: 3.84

Wallclock time: 3.77

Termination condition: optimal

Termination message: Model was solved to optimality (subject to tolerances), and an optimal solution is available.

Statistics:

Branch and bound:

Number of bounded subproblems: None

Number of created subproblems: None

Black box:

Number of iterations: 37773

Error rc: 0

Time: 3.8004262447357178

The only thing I am changing between the two runs is the solver. I can not seem to figure out why CBC gives a feasible solution but CPLEX does not.

Any help is much appreciated!

Thank you in advance,

Marissa

I solved this problem and here is what I did in case it is useful for someone else. I had the wrong term for the solver tolerance defined in my problem. I was able to see this error by adding tee=True as is shown below:

opt = pyomo.SolverFactory(solver)

results = opt.solve(model, tee=True)

By doing this, I was able to see the error that the cplex solver was encountering.