Forum Discussion
Why Mosel result is not as optimal as Gams result?
Hi, I use both Gams and FICO Mosel to solve the same model, but the result from Mosel is not as optimal as the result from Gams. What might cause this difference? 1. It's a MIP problem 2. Set the ...
Hi JW,
Are you using Xpress with GAMS as well? If so, are you using the same version of Xpress with both GAMS and Mosel? Is this also being executed on the same machine?
For a MIP it is quite possible for the performance to change between major releases and some individual instances might get both worse and better due to perturbations introduced by a new version.
Assuming the solver versions are the same and it is being executed on the same machine, it is still possible for GAMS and Mosel to produce slightly different versions of the same problem. For example, the constraints might appear in a different order in the final problem being passed to the solver. Such a small perturbation is often sufficient to send the solver down a different path, and especially for MIPs this can lead to quite different solve times.
I suggest you try writing out the problems being created by both modeling languages, e.g. to an LP file format, where you can check for any differences.
Best Regards,
Michael
