
handle: 11245/1.116985
Consider for \(n = 0, 1, \dots\) the nested spaces \({\mathcal L}_n\) of rational functions of degree \(n\) at most with given poles \(1/ \overline \alpha_i\), \(|\alpha_i |< 1\), \(i = 1, \dots, n\). Let \({\mathcal L} = \cup^\infty_0 {\mathcal L}_n\). Given a finite positive measure \(\mu\) on the unit circle, we associate with it an inner product on \({\mathcal L}\) by \(\langle f,g \rangle = \int f \overline gd \mu\). Suppose \(k_n (z,w)\) is the reproducing kernel for \({\mathcal L}_n\) i.e., \(\langle f(z), k_n (z,w) \rangle = f(w)\), for all \(f \in {\mathcal L}_n\), \(|w |< 1\), then it is known that they satisfy a coupled recurrence relation. In this paper we shall prove a Favard type theorem which says that if you have a sequence of kernel functions \(k_n (z,w)\) which are generated by such a recurrence, then there will be a measure \(\mu\) supported on the unit circle so that \(k_n\) is the reproducing kernel for \({\mathcal L}_n\). The measure is unique under certain extra conditions on the points \(\alpha_i\).
Reproducing kernel, Mathematics, Applied, Numerical & Computational Mathematics, 0102 Applied Mathematics, Zeros of polynomials, rational functions, and other analytic functions of one complex variable (e.g., zeros of functions with bounded Dirichlet integral), Orthogonal rational functions, Favard theorem, REPRODUCING KERNEL, 4901 Applied mathematics, 4613 Theory of computation, Science & Technology, 0103 Numerical and Computational Mathematics, Applied Mathematics, reproducing kernel, orthogonal rational functions, ORTHOGONAL RATIONAL FUNCTIONS, FAVARD THEOREM, 0906 Electrical and Electronic Engineering, Computational Mathematics, Physical Sciences, 4903 Numerical and computational mathematics, Mathematics
Reproducing kernel, Mathematics, Applied, Numerical & Computational Mathematics, 0102 Applied Mathematics, Zeros of polynomials, rational functions, and other analytic functions of one complex variable (e.g., zeros of functions with bounded Dirichlet integral), Orthogonal rational functions, Favard theorem, REPRODUCING KERNEL, 4901 Applied mathematics, 4613 Theory of computation, Science & Technology, 0103 Numerical and Computational Mathematics, Applied Mathematics, reproducing kernel, orthogonal rational functions, ORTHOGONAL RATIONAL FUNCTIONS, FAVARD THEOREM, 0906 Electrical and Electronic Engineering, Computational Mathematics, Physical Sciences, 4903 Numerical and computational mathematics, Mathematics
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