Show current best objective value every 30 minutes

New to AMPL
1

Hello,

I’m solving an ILP problem with AMPL+Cplex. It takes a long time to get optimum solution. I want to output the current found best objective value every 30 minutes. Is it possible with AMPL?

Thank you!

1 Like
2

Hi @qiaolunzhang,

Are you using AMPL via APIs? If that is the case we have solver interfaces with callbacks (https://ampls.readthedocs.io/) that would allow implementing a progress report callback.

3

Hello,

Thank you for your reply. I’m using AMPL directly rather than through any API (e.g., Python). Is there any solution if I"m using AMPL directly?

Thank you!

1 Like
4

Using AMPL directly, you can set the CPLEX option mipdisplay to 1 (e.g., option cplex_options 'mipdisplay=1') and it should display every time a new feasible solution is found. Some other options (CPLEX Options — AMPL Resources) may allow reducing the frequency it displays, but it may not be easy to get just the best objective every 30 minutes.