Status msg: Unknown Status

[goldenhazard]

Hello, I am using the cyipopt v1.4.1 a lot for my project.

During a project, I frequently face the status msg with the b"Unknown status". From my observation, it occurs a lot when the constraint becomes tight, but a feasible solution still exists (Cons < 0).

Could you please advise how to find the cause of this problem (or if a similar issue has been observed, which I cannot find in the issue history.)

Below, I provide how I construct the NLP problem using cyipopt

    nlp = cyipopt.Problem(
        n = n_optvar,
        m = n_constraint,
        problem_obj = problem,
        lb = [-1] * n_optvar,
        ub = [1] * n_optvar,
        cl = [-1e20] * n_constraint,
        cu = [-1e-6] * n_constraint
    )

    nlp.add_option('sb', 'yes')
    nlp.add_option('print_level', 0)
    nlp.add_option('tol', 1e-3)
    nlp.add_option('max_wall_time', self.nlp_time_limit)
    
    k_opt, info = nlp.solve(k_0.cpu().numpy())

[moorepants]

"Unknown status" is returned if cyipopt does not have a specific status message for what IPOPT returns. It is possible that we don't have all status messages implemented for newer IPOPT versions.

[moorepants]

We have 19 status messages here: https://github.com/mechmotum/cyipopt/blob/master/cyipopt/cython/ipopt_wrapper.pyx#L85

which should match those here: https://coin-or.github.io/Ipopt/OUTPUT.html

but there is a mismatch:

Maximum_WallTime_Exceeded present in IPOPT, not in cyipopt

Invalid_Number_Detected present in cyipopt, not in IPOPT

[goldenhazard]

Thanks! it was Maximum_Walltime_exceeded problem.

For future reference, downgrading ipopt version helped not spitting this message.

[moorepants]

We need to update the status messages here to match those available in IPOPT. Thanks for reporting.

[moorepants]

See: https://coin-or.github.io/Ipopt/IpReturnCodes__inc_8h.html#ab542e0b1ca364a9b7525a876ffdae7d7

Maximum_Walltime_exceeded was added in IPOPT 3.14.