ABSTRACT
The general term system description, loosely speaking, refers to a mathematical expression that appropriately relates the physical system quantities to the system components. This mathematical relation constitutes the mathematical model of the system. The mathematical model of a system is a mathematical relation which relates the input, the system, and the output. This relation must be such as to guarantee that one can determine the system’s output for any given input. The problem of determining a system’s mathematical model is essentially a problem of approximating the behavior of a physical system with an ideal mathematical expression. Block diagrams may be considered as a form of system description that provides a simplified overview schematic diagram of a system. Each block is characterized by an input-output description, by its input signal, and by its output signal.
