2. Basic concepts and results

We'll start by studying the differential equations in the state domain, i.e. the time domain. To do this, we'll use mathematical analysis. Using the Laplace transformation, we'll transform these differential equations into algebraic relations in the frequency domain. This will make them easier to study and process. We will then show how to return to the time domain.

For simplicity, we'll assume that $\mathcal{D}$ = 0, which doesn't really restrict generality.