Hi @ElineOoms To find out what it means you should enable CPLEX logging by setting the following options:

• Solvers General option 'Solver listing messages' to 'All'
• CPLEX option 'Barrier display' to 'Normal' or ‘Diagnostics’

If you then rerun the model, CPLEX will create a status file in the log folder. If you need help with understanding this status file then please copy it here.

Hi @Marcel Hunting,

Thank you for the suggestions. I put the logging on (for a run with other inputs, however this run also ends up in intermediate non-optimal) and this is the file I get. It states:

A solution is available, but not proved optimal, due to numeric difficulties during optimization with CPLEX.
A solution is available, but not proved optimal, due to numeric difficulties during the optimization.

How can I avoid these numeric difficulties?

Hi @ElineOoms, 

Enabling the AIMMS scaling tool could be a solution to your problem. This tool is designed eliminate numerical instabilities in your mathematical program. 

You can enable this tool by going to: 

Settings > Project options > Solvers general > Scaling > Scale model

There you can also find more information about the scaling tool, by going to 'Help'.  
Additionally, there is a post about the scaling tool on the Community: https://community.aimms.com/what-s-new-at-aimms-26/marcel-hunting-on-the-aimms-scaling-tool-718

Best regards, 

Toine

Hi @ElineOoms, 

A quick follow up: Currently, CPLEX Barrier crossover is disabled for your model. You could try enabling crossover: 

Settings > Project options > Specific solvers > CPLEX > General > Solution type = Automatic or Basic

Barrier crossover is disabled if the Solution type is set to Non-basic.

Best regards, 

Toine

Hi @Toine,

Thank you very much for your suggestions, we will try this!

Kind regards,

Eline