Rational approximation near zero sets of functions.
The paper deals with the relation between global rational approximation and local approximation off the zero set. Also connections with the problem f2 ∈ R(X) ⇒ f ∈ R(X) are studied.
The paper deals with the relation between global rational approximation and local approximation off the zero set. Also connections with the problem f2 ∈ R(X) ⇒ f ∈ R(X) are studied.
Let ⨍ be an analytic function on a compact subset K of the complex plane ℂ, and let denote the rational function of degree n with poles at the points and interpolating ⨍ at the points . We investigate how these points should be chosen to guarantee the convergence of to ⨍ as n → ∞ for all functions ⨍ analytic on K. When K has no “holes” (see [8] and [3]), it is possible to choose the poles without limit points on K. In this paper we study the case of general compact sets K, when such a separation...