This book is a unique introduction to the theory of linear operators on Hilbert space. The authors goal is to present the basic facts of functional analysis in a form suitable for engineers, scientists, and applied mathematicians. Although the Definition-Theorem-Proof format of mathematics is used, careful attention is given to motivation of the material covered and many illustrative examples are presented. First published in 1971, <b>Linear Operator in</b> <b>Engineering and Sciences</b> has since proved to be a popular and very useful textbook.