This book is the result of our teaching over the years an undergraduate
course on Linear Optimal Systems to applied mathematicians and a
first-year graduate course on Linear Systems to engineers. The contents
of the book bear the strong influence of the great advances in the field
and of its enormous literature. However, we made no attempt to have a
complete coverage. Our motivation was to write a book on linear systems
that covers finite- dimensional linear systems, always keeping in mind
the main purpose of engineering and applied science, which is to
analyze, design, and improve the performance of phy- sical systems.
Hence we discuss the effect of small nonlinearities, and of
perturbations of feedback. It is our on the data; we face robustness
issues and discuss the properties hope that the book will be a useful
reference for a first-year graduate student. We assume that a typical
reader with an engineering background will have gone through the
conventional undergraduate single-input single-output linear systems
course; an elementary course in control is not indispensable but may be
useful for motivation. For readers from a mathematical curriculum we
require only familiarity with techniques of linear algebra and of
ordinary differential equations.