Factorization of Hilbert port operators with poles on the imaginary axis (Q1092391)

In classical network theory scattering, chain and transfer operators corresponding to passive n-ports are meromorphic matrix functions, J- expansive in the right half plane Re p\(>0\), which satisfy the reality condition \(S(\bar p)=\overline{S(p)}.\) The author's abstract: A factorization method is given to extract poles located on the imaginary axis for J-biexpansive meromorphic operator- valued functions acting on an infinite-dimensional Hilbert space. Decomposition of a real operator in terms of real factors, applicable to Hilbert ports, is also described, thus generalizing synthesis techniques originally developed for passive n-ports.