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Proceedings of the American Mathematical Society
Article . 1979 . Peer-reviewed
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Proceedings of the American Mathematical Society
Article . 1979 . Peer-reviewed
Data sources: Crossref
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On an extremal problem

Authors: Paul Nevai;

On an extremal problem

Abstract

Let X = ( x 1 , x 2 , … , x N ) , f : R → C X = ({x_1},{x_2}, \ldots ,{x_N}),f:{\mathbf {R}} \to {\mathbf {C}} and let P n {{\mathbf {P}}_n} be the class of polynomials of degree at most n. The generalized Christoffel function Λ n {\Lambda _n} corresponding to the measure d α d\alpha is defined by \[ Λ n ( X ; f , N , d α ) = min π ∈ P n − 1 π ( x i ) = f ( x i ) i = 1 , 2 , … , N ∫ − ∞ ∞ | π ( t ) | 2 d α ( t ) . {\Lambda _n}(X;f,N,d\alpha ) = \min \limits _{\begin {array}{*{20}{c}} {\pi \in {{\mathbf {P}}_{n - 1}}} \\ {\pi ({x_i}) = f({x_i})} \\ {i = 1,2, \ldots ,N} \\ \end {array} } \int _{ - \infty }^\infty {|\pi (t){|^2}d\alpha (t).} \] It is shown that if α \alpha satisfies some rather weak conditions then lim n → ∞ n Λ n ( X ; f , N , d α ) {\lim _{n \to \infty }}n{\Lambda _n}(X;f,N,d\alpha ) exists and the limit is also evaluated.

Keywords

Christoffel functions, Orthogonal functions and polynomials, general theory of nontrigonometric harmonic analysis, orthogonal polynomials

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citations
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
2
Average
Average
Average
bronze