search

coin-or / Couenne

Convex Over and Under Envelopes for Nonlinear Estimation
Eclipse Public License 1.0
69 stars 7 forks source link

No solution/ Time Limit Reached Error in Couenne #54

Closed Jainendra1712 closed 3 years ago

Jainendra1712 commented 3 years ago

Dear All, I am working on pyomo and running an optimization program on google colab (Optimizer/Solver is Couenne). I am getting an error as: "No Solution" "NLP Heuristic: time limit reached"

The results I am getting are not matching with my GAMS optimization.

I already tried the option of writing "time_limit 100" in couenne.opt file. But still my code is running for less than 2 seconds. I don't know because of what reasons I am not getting a solution.

Link for the code: https://colab.research.google.com/drive/12G0M5NGf8BkhxYmK5jdFf5ulBbtnOG28?usp=sharing

Thank You

tkralphs commented 3 years ago

It looks to me like it's running for two seconds because that's how long it takes to solve to optimality. The output indicates it has found the optimum, unless I'm misinterpreting. These lines are the important ones:

Lower bound:                               -17240
Upper bound:                               -17240  (gap: 0.00%)

The lines indicating the NLP heuristic has reached its time limit are just informational and don't indicate an issue, there is just a time limit on the heuristic (but I think this time limit is 2 seconds, so it's a mystery to me how it can time out so many times within a three-second run).

Jainendra1712 commented 3 years ago

Error was in writing the code.