The default Automatic setting of LPMethod lets ILOG CPLEX decide which algorithm to use to optimize your problem. Most models are solved well with this setting, and this is the recommended option except when you have a compelling reason to tune performance for a particular class of model.

On a serial computer, or on a parallel computer where only one thread will be invoked, the automatic setting will in most cases choose the dual simplex optimizer. An exception to this rule is when an advanced basis is present that is ascertained to be primal feasible; in that case, primal simplex will be called.

On a computer where parallel threads are available to ILOG CPLEX, the automatic setting results in the dual simplex optimizer being called if the parallel mode is deterministic, and in the concurrent optimizer being called if the parallel mode is opportunistic. An exception to this rule occurs when an advanced basis is present; in that case, it will behave as the serial algorithm would.