Computation of the singular values of Toeplitz operators and the gap metric

It is widely recognized that the computation of gap metric is equivalent to a certain two-block H-infinity problem. i.e.. the gap is equal to the norm of a certain two-block operator. However, it can also be characterized as the smallest singular value of a certain Toeplitz operator. This paper deri ves a simple computational method for finding such singular values and the gap between two plants by using a stare space approach. (C) 1999 Elsevier S cience B.V. All rights reserved.