A central role in the theory of discrete-time linear systems is played by the idea that every such system has an input-output map that can be represented by a convolution or the familiar generalization of a convolution. This thinking involves an oversight that was recently corrected by adding an additional term to the representation. A need for an additional term arises also in connection with representations for continuous-time linear systems. We survey these results and describe a corresponding very recent result for the important case of representations of multidimensional continuous-space system maps.

Biography

Irwin W. Sandberg received the B. E. E., M. E. E., and D. E. E. degrees from the Polytechnic Institute of Brooklyn (now Polytechnic University) in 1955, 1956, and 1958, respectively (Westinghouse Fellow 1956, Bell Laboratories Fellow 1957 and 1958).

He is presently a Professor of Electrical and Computer Engineering at The University of Texas at Austin, where he holds the Cockrell Family Regents Chair in Engineering, No. 1. Between 1958 and 1986 he was with Bell Laboratories, Murray Hill, New Jersey (as a Member of Technical Staff in the Mathematics and Statistics Research Center, and as Head of the Systems Theory Research Department from 1967 to 1972).

He has been concerned with analysis of radar systems for military defense, with synthesis and analysis of linear networks, with several studies of qualitative properties of nonlinear systems (with emphasis on the development of input-output stability theory), and with some problems in communication theory and numerical analysis. His more recent interests include studies of the approximation and signal-processing capabilities of nonlinear networks.

He received the first Technical Achievement Award of the IEEE Circuits and Systems Society, is a Fellow of the American Association for the Advancement of Science, a Life Fellow of the IEEE, an IEEE Centennial Medalist, an Outstanding Alumnus of Polytechnic University, a former Vice Chairman of the IEEE Group on Circuit Theory, a former Guest Editor of the IEEE Transactions on Circuit Theory Special Issue on Active and Digital Networks, and a former Guest Co-Editor of the {IEEE Transactions on Circuits and Systems} Darlington Memorial Issue. He has published extensively and holds nine patents.

Dr. Sandberg is listed in several reference volumes, such as Who's Who in America, and has been an advisor to American Men and Women of Science. He has received outstanding paper awards, an ISI Press Classic Paper Citation, a Bell Laboratories Distinguished Staff Award, and is a member of SIAM, Eta Kappa Nu, Sigma Xi, Tau Beta Pi, and the National Academy of Engineering.