[Couenne] Errors while solving a (convex quadratic) model

[David Papp]

Hi,

I ran into a problem using Couenne (with AMPL), getting either the wrong answer (problem is infeasible), or an exception, depending on the version I use. I tried both the precompiled binaries, the latest version compiled on my computer, and also the version on NEOS, all with default settings. The minimal example is really simple, the AMPL model file is:

var X;
var Y;
minimize obj: X;
subject to c: X-Y^2 >= 0;

I also get different wrong results if I replace Y^2 by Y*Y. (Some versions crash on one, and "solve" the other, claiming it's infeasible.) The problems seem to be on the solver side, as the same model files work with Ipopt. The original example was non-convex, which is why I'm trying to get Couenne work.

Thanks,
David

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