共查询到20条相似文献,搜索用时 15 毫秒
1.
M. J. Johnson 《Constructive Approximation》1997,13(2):155-176
An upper bound on theL
p-approximation power (1 ≤p ≤ ∞) provided by principal shift-invariant spaces is derived with only very mild assumptions on the generator. It applies
to both stationary and nonstationary ladders, and is shown to apply to spaces generated by (exponential) box splines, polyharmonic
splines, multiquadrics, and Gauss kernel. 相似文献
2.
We investigate limiting behavior as γ tends to ∞ of the best polynomial approximations in the Sobolev-Laguerre space WN,2([0, ∞); e−x) and the Sobolev-Legendre space WN,2([−1, 1]) with respect to the Sobolev-Laguerre inner product
and with respect to the Sobolev-Legendre inner product
respectively, where a0 = 1, ak ≥0, 1 ≤k ≤N −1, γ > 0, and N ≥1 is an integer. 相似文献
3.
V. N. Temlyakov 《Constructive Approximation》1992,8(1):23-33
We obtain estimates of approximation numbers of integral operators, with the kernels belonging to Sobolev classes or classes of functions with bounded mixed derivatives. Along with the estimates of approximation numbers, we also obtain estimates of best bilinear approximation of such kernels.Communicated by Charles A. Micchelli. 相似文献
4.
We show that ifw(x)=exp(–|x|), then in the case =1 for every continuousf that vanishes outside the support of the corresponding extremal measure there are polynomialsP
n of degree at mostn such thatw
n
P
n uniformly tends tof, and this is not true when <1. these=" are=" the=" missing=" cases=" concerning=" approximation=" by=" weighted=" polynomials=" of=" the=">1.>w
n
P
n wherew is a Freud weight. Our second theorem shows that even if we are only interested in approximation off on the extremal support, the functionf must still vanish at the endpoints, and we actually determine the (sequence of) largest possible intervals where approximation is possible. We also briefly discuss approximation by weighted polynomials of the formW(anx)P
n
(x).Communicated by Edward B. Saff. 相似文献
5.
We investigate best uniform approximations to bounded, continuous functions by harmonic functions on precompact subsets of Riemannian manifolds. Applications to approximation on unbounded subsets ofR
2 are given.Communicated by J. Milne Anderson. 相似文献
6.
I. R. H. Jackson 《Constructive Approximation》1988,4(1):243-264
The multivariate interpolation problem is that of choosing a functions fromR toR that satisfies the interpolation conditions
相似文献
7.
Winfried Sickel 《Constructive Approximation》1992,8(3):257-274
Let
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