Important terms in Control Theory

A control system consists of

Inputs, which are things that we can not only measure, but to which we can assign chosen values (constants or functions of time). Examples: Drug dosages and treatment regimens.

Outputs, which are things that we can measure, but to which we cannot assign values. Examples: Concentrations of administered drug in urine, blood, etc.

States, which are things that affect the outputs, but which cannot even measure because we cannot directly access them. Examples: Concentrations of drug in targeted organ.

Trivial. A solution or example that is ridiculously simple and of little interest. Often, solutions or examples involving the number 0 are considered trivial. Nonzero solutions or examples are considered nontrivial.

Causality (also referred to as causation, or cause and effect) is the agency or efficacy that connects one process (the cause) with another process or state (the effect), where the first is understood to be partly responsible for the second, and the second is dependent on the first.

A singularity means a point where some property is infinite. For example, at the center of a black hole, according to classical theory, the density is infinite (because a finite mass is compressed to a zero volume). Hence it is a singularity.

Stochastic : For a system to be stochastic, one or more parts of the system has randomness associated with it. Unlike a deterministic system.