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Approximation by semigroup of spherical operators |
Yuguang WANG,Feilong CAO() |
Department of Mathematics, China Jiliang University, Hangzhou 310018, China |
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Abstract This paper concerns about the approximation by a class of positive exponential type multiplier operators on the unit sphere Sn of the (n + 1)-dimensional Euclidean space for n≥2.We prove that such operators form a strongly continuous contraction semigroup of class (C0) and show the equivalence between the approximation errors of these operators and the K-functionals. We also give the saturation order and the saturation class of these operators. As examples, the rth Boolean of the generalized spherical Abel-Poisson operator ⊕rVtγ and the rth Boolean of the generalized spherical Weierstrass operator ⊕rWtk for integer r≥1 and reals γ, κ∈ (0, 1] have errors ∥⊕rVtγf-f∥X≈ωrγ(f,t1/γ)X and ∥⊕rWtkf-f∥X≈ω2rk(f,t1/(2k))X for all f∈X and 0≤t≤2π, where Xis the Banach space of all continuous functions or all Lpintegrable functions, 1≤p<+∞, on Sn with norm ∥⋅∥X, and ωs(f,t)Xis the modulus of smoothness of degree s>0 for f∈X. Moreover, ⊕rVtγ and ⊕rWtk have the same saturation class if γ=2κ.
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Keywords
Sphere
semigroup
approximation
modulus of smoothness
multiplier
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Corresponding Author(s):
Feilong CAO
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Issue Date: 16 May 2014
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1 |
AskeyR, WaingerS. On the behavior of special classes of ultraspherical expansions, I. J d’Analyse Math, 1965, 15: 193-220 doi: 10.1007/BF02787693
|
2 |
AskeyR, WaingerS. On the behavior of special classes of ultraspherical expansions, II. J d’Analyse Math, 1965, 15: 221-244 doi: 10.1007/BF02787694
|
3 |
BerensH, ButzerP L, PawelkeS. Limitierungsverfahren von reihen mehrdimensionaler kugelfunktionen und deren saturationsverhalten. Publ Res Inst Math Sci Ser A, 1968, 4(2): 201-268 doi: 10.2977/prims/1195194875
|
4 |
BochnerS. Quasi analytic functions, Laplace operator, positive kernels. Ann Math, 1950, 51(1): 68-91 doi: 10.2307/1969498
|
5 |
BochnerS. Sturm-Liouville and heat equations whose eigenfunctions are ultraspherical polynomials or associated Bessel functions. In: Proceedings of the Conference on Differential Equations. University of Maryland, 1955, 23-48
|
6 |
ButzerP L, BerensH. Semi-groups of Operators and Approximation. Berlin: Springer, 1967 doi: 10.1007/978-3-642-46066-1
|
7 |
DaiF. Some equivalence theorems with K-functionals. J Approx Theory, 2003, 121: 143-157 doi: 10.1016/S0021-9045(02)00059-X
|
8 |
DaiF, DitzianZ. Strong converse inequality for Poisson sums. Proc Amer Math Soc, 2005, 133(9): 2609-2611 doi: 10.1090/S0002-9939-05-08089-5
|
9 |
DitzianZ, IvanovK. Strong converse inequalities. J d’Analyse Math, 1993, 61: 61-111 doi: 10.1007/BF02788839
|
10 |
DunklC F. Operators and harmonic analysis on the sphere. Trans Amer Math Soc, 1966, 125(2): 250-263 doi: 10.1090/S0002-9947-1966-0203371-9
|
11 |
FavardJ. Sur l’approximation des fonctions d’une variable reelle. Colloque d’Anal Harmon Publ CNRS, Paris, 1949, 15: 97-110
|
12 |
KaczmarzS, SteinhausH. Theorie der Orthogonalreihen. Warsaw: Instytut Matematyczny Polskiej Akademi Nauk, 1935
|
13 |
KuttnerB. On positive Riesz and Abel typical means. Proc Lond Math Soc Ser 2, 1947, 49(1): 328-352
|
14 |
RiemenschneiderS, WangK Y. Approximation theorems of Jackson type on the sphere. Adv Math (China), 1995, 24(2): 184-186
|
15 |
SzegöG. Orthogonal Polynomials. Providence: Amer Math Soc, 2003
|
16 |
WangK Y, LiL Q. Harmonic Analysis and Approximation on the Unit Sphere. Beijing: Science Press, 2006
|
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