Introducing Delay in Linear Time-Periodic Systems

Dynamical systems have been described with differential equations since the appearance of the differential calculus; Newton’s second law could be considered one of the first examples. A differential equation can serve as a model for how the rate of change of state depends on the present state of a system. However, the rate of change of state may depend on past states, too. It has been known for a long time that several problems can be described by models including past effects.