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Journal Articles Journal of Approximation Theory Year : 2009

Multipoint Padé Approximants to Complex Cauchy Transforms with Polar Singularities

Abstract

We study diagonal multipoint Padé approximants to functions of the form \[F(z) = \int\frac{d\mes(t)}{z-t}+R(z),\] where $R$ is a rational function and $\mes$ is a complex measure with compact regular support included in $\R$, whose argument has bounded variation on the support. Assuming that interpolation sets are such that their normalized counting measures converge sufficiently fast in the weak-star sense to some conjugate-symmetric distribution $\sigma$, we show that the counting measures of poles of the approximants converge to $\widehat\sigma$, the balayage of $\sigma$ onto the support of $\mes$, in the weak$^*$ sense, that the approximants themselves converge in capacity to $F$ outside the support of $\mes$, and that the poles of $R$ attract at least as many poles of the approximants as their multiplicity and not much more.
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Dates and versions

inria-00119160 , version 1 (08-12-2006)
inria-00119160 , version 2 (02-08-2010)

Identifiers

  • HAL Id : inria-00119160 , version 2

Cite

Laurent Baratchart, Maxim Yattselev. Multipoint Padé Approximants to Complex Cauchy Transforms with Polar Singularities. Journal of Approximation Theory, 2009, 156 (2), pp.187-211. ⟨inria-00119160v2⟩

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