ELA, Volume 11, pp. 1-15, January 2004, abstract.
On the Krein-Langer Integral Representation of
Generalized Nevanlinna Functions
by
J. Rovnyak and L.A. Sakhnovich
The Krein-Langer integral representation of a matrix-valued
generalized Nevanlinna function arises in problems of spectral
theory and interpolation. A version of this formula which is
suitable for such problems, and a corresponding Stieltjes inversion
formula, are derived. Some classes of generalized Nevanlinna
functions which are defined in terms of behavior at infinity are
characterized in terms of their integral representations.