Formulations using indicator constraints can be more numerically robust and accurate than conventional formulations involving so-called Big M data. Big M formulations use artificial data to turn on or turn off enforcement of a constraint. Big M formulations often exhibit trickle flow, and sometimes they behave in unstable ways.

In Concert Technology applications, ILOG CPLEX automatically uses indicator constraints for you when it encounters a constraint within an expression and when it encounters expressions which can be linearized, including the following:

In Callable Library applications, you can invoke the routine CPXaddindcontr yourself to introduce indictor constraints in your model. To remove an indicator constraint that you have added, use the routine CPXdelindconstr.