## Abstract We consider an interpolation problem of Nevanlinna–Pick type for matrix‐valued Carathéodory functions, where the values of the functions and its derivatives up to certain orders are given at finitely many points of the open unit disk. For the non‐degenerate case, i.e., in the particular
An indeterminate rational moment problem and Carathéodory functions
✍ Scribed by Adhemar Bultheel; Pablo González-Vera; Erik Hendriksen; Olav NjÅstad
- Publisher
- Elsevier Science
- Year
- 2008
- Tongue
- English
- Weight
- 177 KB
- Volume
- 219
- Category
- Article
- ISSN
- 0377-0427
No coin nor oath required. For personal study only.
✦ Synopsis
Let { n } ∞ n=1 be a sequence of points in the open unit disk in the complex plane and let
. We put L = span{B n : n = 0, 1, 2, . . .} and we consider the following "moment" problem: Given a positive-definite Hermitian inner product •, • in L, find all positive Borel measures on [-, ) such that
We assume that this moment problem is indeterminate. Under some additional condition on the n we will describe a one-to-one correspondence between the collection of all solutions to this moment problem and the collection of all Carathéodory functions augmented by the constant ∞.
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