[Couenne] couenne doesn't exit normally -- Code in Pyomo

[Ouanes, Nesrine]

Hi all,


I want to solve my code, which is written in Python and Pyomo, with Couenne.

I get an error (Solver (asl) did not exit normally) with no further information , whenever I try to solve a code with a division, e.g. I have the following constraint:


r_p = p2/p1


p1, p2 and r_p are variables in my model. I made sure that the bounds for p1 don't include the value 0.


All other constraints are linear and have no divisions. Couenne works fine, when I comment this constraint out. Strangely, Couenne also works fine, if I write the constraint as follows:


r_p = p * (p1)^(-1)

As I'm going to further develop my model and it will eventually have very high nonlinearities, I seek your help in understanding, why this problem occurs.

Can this be a bug within Couenne? Or perhaps in the Solver interface in Pyomo?


Looking forward to your response.


Best,

Nesrine



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