Displaying similar documents to “A survey on the Weierstrass approximation theorem.”

A counterexample in comonotone approximation in L p space

Xiang Wu, Song Zhou (1993)

Colloquium Mathematicae

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Refining the idea used in [24] and employing very careful computation, the present paper shows that for 0 < p ≤ ∞ and k ≥ 1, there exists a function f C [ - 1 , 1 ] k , with f ( k ) ( x ) 0 for x ∈ [0,1] and f ( k ) ( x ) 0 for x ∈ [-1,0], such that lim supn→∞ (en(k)(f)p) / (ωk+2+[1/p](f,n-1)p) = + ∞ where e n ( k ) ( f ) p is the best approximation of degree n to f in L p by polynomials which are comonotone with f, that is, polynomials P so that P ( k ) ( x ) f ( k ) ( x ) 0 for all x ∈ [-1,1]. This theorem, which is a particular case of a more general one, gives a complete...

On some properties of the Picard operators

Lucyna Rempulska, Karolina Tomczak (2009)

Archivum Mathematicum

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We consider the Picard operators 𝒫 n and 𝒫 n ; r in exponential weighted spaces. We give some elementary and approximation properties of these operators.

Strong uniqueness.

Kroó, András, Pinkus, Allan (2010)

Surveys in Approximation Theory (SAT)[electronic only]

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