Introduction

Abstract

System. A system is a collection of objects arranged in an ordered form to serve some purpose. Everything not belonging to the system is part of the environment. One may characterize the system by input/output (cause and effect) relations. What constitutes a system depends on the point of view of the observer. The system may be, for example, an amplifier consisting of electronic components, or a control loop including that amplifier as one of its parts, or a chemical processing unit having many such loops, or a plant consisting of a number of units or a number of plants operating together as a system in the environment of a global economy.