On Boundary Interpolation for Matrix Valued Schur Functions

Download or read book On Boundary Interpolation for Matrix Valued Schur Functions written by Vladimir Bolotnikov and published by American Mathematical Soc.. This book was released on 2006 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: A number of interpolation problems are considered in the Schur class of $p\times q$ matrix valued functions $S$ that are analytic and contractive in the open unit disk. The interpolation constraints are specified in terms of nontangential limits and angular derivatives at one or more (of a finite number of) boundary points. Necessary and sufficient conditions for existence of solutions to these problems and a description of all the solutions when these conditions are met is given. The analysis makes extensive use of a class of reproducing kernel Hilbert spaces ${\mathcal{H}}(S)$ that was introduced by de Branges and Rovnyak. The Stein equation that is associated with the interpolation problems under consideration is analyzed in detail. A lossless inverse scattering problem is also considered.