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