[Couenne] Printing best solution found when time limit exceeded

[Ouanes, Nesrine]

Hello,


I'm solving a NLP Problem with couenne. My model is written in Python and Pyomo.


In my case, Couenne takes very long without exiting with an optimal solution. The best solution is given after a few iterations and doesn't change after hours of execution:


Cbc0010I After 7100 nodes, 3364 on tree, 0.25239475 best solution, best possible 0.15 (14.72 seconds)


Therefore, I've set the option time_limit to a smaller value (100 seconds), to be able to retrieve the best solution found so far and print it to a file. However couenne prints another solution than the one stated in the solver log:


instead of 0.25239475, I get 0.281323177 as a value for the objective function.


The value printed by Couenne is the same one I get if I solve my model using Ipopt.


1) Do you have any idea, why this occurs?  Is it possible that Couenne is printing the best solution found by ipopt, since it's used in Couenne?


2) Is there a way to obtain the better solution given in the solver log?


I look forward to your reply.


Best,

Nesrine



?






-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://list.coin-or.org/pipermail/couenne/attachments/20180425/560c8db9/attachment.html>