This book is written for the wide circle of readers who take an interest in concepts of basic sciences, specifically cybernetics, automation and control. It aims to provide a new technique for the solution of a range of automatic control problems using n ew types of feedback loops. Simple examples are used to illustrate the basic problems, the important aspects of the theory of automatic control and the difficulties that have to be faced when considering the automation of actual objects. Control of Indefinite Nonlinear Dynamic Systems is the first book to set out an effective regular procedure for the synthesis of robust feedback loops. This signifies an advancement in the area of general feedback which deal with problems of robust contro l under conditions of uncertainty.