Polynomial computation of Hankel singular values

A revised and improved version of a polynomial algorithm is presented. It was published by N.J. Young (1990) for the computation of the singular values and vectors of the Hankel operator defined by a linear time-invariant system with a rotational transfer matrix. Tentative numerical experiments indicate that for high-order systems, scaling of the polynomial matrices N and D (so that the constant and leading coefficient matrices are of the same order of magnitude) is mandatory, and that solution of bilateral linear polynomial matrix equations by coefficient expansion is highly inefficient