For every bivariate polynomial p( z(1), z(2)) of bidegree ( n(1), n(2)), with p( 0, 0) = 1, which has no zeros in the open unit bidisk, we construct a determinantal representation of the form p( z1, z2) = det( I - K Z), where Z is an ( n1 + n2) x( n1 + n2) diagonal matrix with coordinate variables z1, z2 on the diagonal and K is a contraction. We show that K may be chosen to be unitary if and only if p is a ( unimodular) constant multiple of its reverse. Furthermore, for every bivariate real-zero polynomial p( x(1), x(2)), with p( 0, 0) = 1, we provide a construction to build a representation of the form p( x1, x2) = det( I + x(1)A(1) + x2 A(2)), where A(1) and A2 are Hermitian matrices of size equal to the degree of p. A key component of both constructions is a stable factorization of a positive semidefinite matrix- valued poly-nomial in one variable, either on the circle ( trigonometric polynomial) or on the real line ( algebraic polynomial).
Dmitry S. Kaliuzhnyi-Verbovetskyi - Drexel University
Victor Vinnikov - Ben-Gurion University of the Negev
Hugo J. Woerdeman - Drexel University
Publication Details
Multidimensional systems and signal processing, v 27(1), pp 1-26
Publisher
Springer Nature
Number of pages
26
Grant note
Institute for Mathematical Sciences of the National University of Singapore; National University of Singapore
2010432 / BSF; US-Israel Binational Science Foundation
DMS-0901628 / NSF; National Science Foundation (NSF)
Resource Type
Journal article
Language
English
Academic Unit
Mathematics
Web of Science ID
WOS:000367895200001
Scopus ID
2-s2.0-84953638074
Other Identifier
991019168246604721
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