The present book deals with canonical factorization problems for
di?erent classes of matrix and operator functions. Such problems appear
in various areas of ma- ematics and its applications. The functions we
consider havein common that they appear in the state space form or can
be represented in such a form. The main results are all expressed in
terms of the matrices or operators appearing in the state space
representation. This includes necessary and su?cient conditions for
canonical factorizations to exist and explicit formulas for the
corresponding f- tors. Also, in the applications the entries in the
state space representation play a crucial role.
Thetheorydevelopedinthebookisbasedonageometricapproachwhichhas its
origins in di?erent ?elds. One of the initial steps can be found in
mathematical systems theory and electrical network theory, where a
cascade decomposition of an input-output system or a network is related
to a factorization of the associated transfer function. Canonical
factorization has a long and interesting history which starts in the
theory of convolution equations. Solving Wiener-Hopf integral equations
is closely related to canonical factorization. The problem of canonical
factorization also appears in other branches of applied analysis and in
mathematical systems theory, in H -control theory in particular.