first of all, what is an "optimal control law" or actually a "control law"? is it the equation that defines your control variable/vector u ?

second of all ... I'm taking "optimal control" right now as a grad course and, while it's too early to tell, for now the course has been mainly math and optimisation. how to find the minimum "something" with some constraints, and variations on this theme.

let's say I solve the problem and find the equations that define my optimal control law, whatever that is... let's say for a multivariable ssytem in state space.

how do I actually make a control system for this? in practical real world terms...