Using MINLP with Pyomo

[Jaime Vera]

Good Morning everybody!

I have installed the MINLP Couenne solver from the COIN-OR project, and i've tried to use with Pyomo as an ASL solver but i get the following message:

The SolverFactory was unable to create the solver "couenne"
and returned an UnknownSolver object.  This error is raised at the point
where the UnknownSolver object was used as if it were valid (by calling
method "solve").

The original solver was created with the following parameters:
    type: couenne
    _args: ()
    options: {}

Can anyone enlighten me about the problem? As far as i know, i have installed the solver correctly!

Thanks in advance!!

Jaime

[Gabriel Hackebeil]

The directory containing the ‘couenne' executable needs to be in the search path defined by the PATH environment variable. That is, you need to be able to launch ‘couenne' from your terminal from any directory.

Alternatively (and only because Couenne uses the NL-file interface), you could set the solver name to the absolute path to the ‘couenne’ executable (e.g., /usr/local/bin/couenne).

Gabe

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[Jaime Vera]

I think that is not the problem, because i have the ipopt executable in the same path, and it works perfectly.

[Jaime Vera]

Dear Gabe,

I have tried setting the name of the solver to the path of the couenne executable, but still get the same message. I worder if may be some issue with the cygwin environment, because i have installed the couenne for windows using the cygwin following a procedure similar to the installation of the Ipopt.

Jaime

[Gabe Hackebeil]

Are you executing Pyomo in a Cygwin shell?

Also, have you confirmed that you can launch Couenne from any directory in whatever shell you are launching Pyomo from? Answering this question does not require using Pyomo.

Gabe