Spectral Factorization by Symmetric Extraction for Distributed Parameter Systems

The spectral factorization problem of a scalar coercive spectral density is considered in the framework of the CallierDesoer algebra of distributed parameter system transfer functions. Criteria for the infinite product representation of a coercive spectral density and for the convergence of infinite product representations of spectral factors, i.e. for the convergence of the symmetric extraction method for solving the spectral factorization problem, are described and commented. These theoretical results of concergence are illustrated by some examples.