Stability and Control of Linear Systems

Many phenomena observed in the real world, regardless to their different nature, involve several physical quantities and result from the interaction of various components: for these reasons, in these situations the term “system” is generally used.
The experimental information obtained by studying a physical system gives often rise to the construction of a mathematical model. In this way, it can be easily communicated and elaborated qualitatively or numerically, and possibly employed to control the evolution of the system. In this book, the term system will be often referred to the mathematical model, rather than the represented real phenomenon.
Without any pretence of giving an axiomatic definition, the present introductory chapter aims to describe informally the main features of the notion of system, and the way we can take advantages of them.