Factorial-type Schur functions, orthogonal rational functions, and discrete dressing chains

2016 ◽  
Vol 57 (5) ◽  
pp. 052701
Author(s):  
Ryosuke Miyaura ◽  
Atsushi Mukaihira
Keyword(s):  
Schur Functions ◽  
Rational Functions ◽  
Orthogonal Rational Functions

scholarly journals Solution of a multiple Nevanlinna–Pick problem for Schur functions via orthogonal rational functions

Analysis ◽  
2008 ◽  
Vol 28 (1) ◽  
Author(s):  
Adhemar Bultheel ◽  
Andreas Lasarow
Keyword(s):  
Unique Solution ◽  
Interpolation Problem ◽  
Schur Functions ◽  
Rational Functions ◽  
Open Unit ◽  
Open Unit Disk ◽  
Orthogonal Rational Functions ◽  
All Solutions ◽  
Pick Problem ◽  
Complex Valued

An interpolation problem of Nevanlinna–Pick type for complex-valued Schur functions in the open unit disk is considered. We prescribe the values of the function and its derivatives up to a certain order at finitely many points. Primarily, we study the case that there exist many Schur functions fulfilling the required conditions. For this situation, an application of the theory of orthogonal rational functions is used to characterize the set of all solutions of the problem in question. Moreover, we treat briefly the case of exactly one solution and present an explicit description of the unique solution in that case.

scholarly journals SCHUR–NEVANLINNA SEQUENCES OF RATIONAL FUNCTIONS

2007 ◽  
Vol 50 (3) ◽  
pp. 571-596 ◽  
Author(s):  
Adhemar Bultheel ◽  
Andreas Lasarow
Keyword(s):  
Unit Circle ◽  
Interpolation Problem ◽  
Schur Functions ◽  
Rational Functions ◽  
The Other ◽  
Complex Numbers ◽  
Orthogonal Rational Functions ◽  
All Solutions ◽  
The One

AbstractWe study certain sequences of rational functions with poles outside the unit circle. Such kinds of sequences are recursively constructed based on sequences of complex numbers with norm less than one. In fact, such sequences are closely related to the Schur–Nevanlinna algorithm for Schur functions on the one hand, and to orthogonal rational functions on the unit circle on the other. We shall see that rational functions belonging to a Schur–Nevanlinna sequence can be used to parametrize the set of all solutions of an interpolation problem of Nevanlinna–Pick type for Schur functions.

scholarly journals Orthogonal rational functions and modified approximants

1996 ◽  
Vol 11 (1) ◽  
pp. 57-69 ◽  
Author(s):  
A. Bultheel ◽  
P. González-Vera ◽  
E. Hendriksen ◽  
O. Njåstad
Keyword(s):  
Rational Functions ◽  
Orthogonal Rational Functions

scholarly journals Convergence of modified approximants associated with orthogonal rational functions

1995 ◽  
Vol 57 (1-2) ◽  
pp. 77-86 ◽  
Author(s):  
A. Bultheel ◽  
P. González-Vera ◽  
E. Hendriksen ◽  
O. Njåstad
Keyword(s):  
Rational Functions ◽  
Orthogonal Rational Functions

The Zero Distribution of Orthogonal Rational Functions on the Unit Circle

1997 ◽  
Vol 49 (4) ◽  
pp. 810-819
Author(s):  
K. Pan
Keyword(s):  
Unit Circle ◽  
Potential Theory ◽  
Rational Functions ◽  
Orthogonal Rational Functions ◽  
Zero Distribution

AbstractRational functions orthogonal on the unit circle with prescribed poles lying outside the unit circle are studied. We use the potential theory to discuss the zeros distribution for the orthogonal rational functions.

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