When does AMPL evaluate the conditions specified in my model’s check statements?

The check conditions are evaluated each time that AMPL generates (or re-generates) an instance of your model. Normally the generation of an instance is triggered by a solve command, but a few other commands such as write and solution can have the same effect.

You can force all check statements to be evaluated immediately by typing the command


or by inserting this command into an AMPL script at the point where you want the checking to occur.