共查询到20条相似文献,搜索用时 78 毫秒
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在最大框架下研究基于第二类Tchebyshev节点组的拟Hermite插值算子和Hermite插值算子对一个解析函数类的逼近误差.对于一致范数,我们得到了相应量的精确值.对于L_p-范数(1≤p∞),我们得到了相应量的值或强渐近阶. 相似文献
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具有Gauss测度的Sobolev空间上的函数逼近 总被引:1,自引:0,他引:1
本文讨论了具有Gauss测度的Sobolev空间上的一元周期函数被三角多项式子空间的最佳逼近及被Fourier部分和算子,Vallée—Poussin算子,Ceshxo算子,Abel算子和Jackson算子的逼近,得到了平均误差估计.证明了在平均框架下,在Lq(1≤q〈∞)空间尺度下三角多项式子空间是渐进最优的子空间,但是在L∞空间尺度下,三角多项式子空间不是渐进最优的子空间.还证明了,Fourier部分和算子和Vallée-Poussin算子在Lq(1≤q≤∞)空间尺度下是渐进最优的线性算子.注意到在平均框架以及Lq(1≤q〈∞)空间尺度下,渐进最优的线性算子,如Fourier部分和算子及Vallée—Poussin算子,与最优的非线性算子的逼近效果一样好. 相似文献
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在第一种边界条件下,我们证明了二重、三重、四重叠二次样条插值以h_2的精度分别逼近光滑函数的一阶、二阶、三阶导数,并说明对适当提出的边界条件.叠二次样条插值可以在h_2的精度范围内逼近光滑函数的其它阶导数. 相似文献
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本文通过揭示一元样条与二元样条的本质联系和构造两种局部区域上的插值函数,从而改进了[1]中S_2~1(△_(mn)~(2))上插值的误差估计结果。 相似文献
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本文考虑某些函数类在L~P尺度下的精确逼近阶问题.这是S.Bernstein,S.Nikol'ski和M.Hasson的一系列研究的继续和推广,作为特例,本文主要结果的应用包含了B.K.最近的工作. 相似文献
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Let be the usual Sobolev class of functions on the unit ball in , and be the subclass of all radial functions in . We show that for the classes and , the orders of best approximation by polynomials in coincide. We also obtain exact orders of best approximation in of the classes by ridge functions and, as an immediate consequence, we obtain the same orders in for the usual Sobolev classes . 相似文献
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复变量移动最小二乘近似在Sobolev空间中的误差估计 总被引:4,自引:4,他引:0
复变量移动最小二乘近似是形成无网格法形函数的重要方法,为了研究相应的无网格方法的误差估计,需要先分析复变量移动最小二乘近似的逼近误差.首先介绍了复变量移动最小二乘近似,接着在权函数满足一定假设的条件下,详细讨论了复变量移动最小二乘近似逼近函数在Sobolev空间中的误差估计,给出了逼近函数在Hk范数下的误差界,分析结果表明逼近函数的误差随着节点间距的减小而降低.最后给出了一个数值算例来验证理论分析的正确性. 相似文献
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We study the approximation of the imbedding of functions from anisotropic and general-ized Sobolev classes into Lq([0,1]d) space in the quantum model of computation. Based on the quantum algorithms for approximation of finite imbedding from LpN to LNq , we develop quantum algorithms for approximating the imbedding from anisotropic Sobolev classes B(Wpr ([0,1]d)) to Lq([0,1]d) space for all 1 q,p ∞ and prove their optimality. Our results show that for p < q the quantum model of computation can bring a speedup roughly up to a squaring of the rate in the classical deterministic and randomized settings. 相似文献
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In this paper, we study the pointwise approximation of functions defined on the real semiaxis and having an rth derivative bounded almost everywhere. The approximation is performed by means of entire functions of bounded half-degree, which were introduced by S. N. Bernstein. An asymptotically sharp estimate for pointwise approximation of this class of functions is obtained. 相似文献
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《Journal of Approximation Theory》2003,120(2):185-216
The density of polynomials is straightforward to prove in Sobolev spaces Wk,p((a,b)), but there exist only partial results in weighted Sobolev spaces; here we improve some of these theorems. The situation is more complicated in infinite intervals, even for weighted Lp spaces; besides, in the present paper we have proved some other results for weighted Sobolev spaces in infinite intervals. 相似文献
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M. -B. A. Babaev 《Mathematical Notes》1997,62(1):15-29
We study the approximation of functions of several variables by bilinear forms that are the pairwise products of functions
of fewer variables. The order of approximation of Sobolev classesW
q
r
by bilinear forms inL
p
for 2≤q≤p≤∞ is found.
Translated by N. K. Kulman
Translated fromMatematicheskie Zametki, Vol. 62, No. 1, pp. 18–34, July, 1997. 相似文献
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Sorin G> Gal 《Journal of Computational Analysis and Applications》2000,2(3):265-276
Starting from the equivalence between the Ditzian–Totik modulus
and
, where
, in this article large classes of functions
are introduced for which the modulus
can be easily calculated. As a consequence, very good estimates for the bestapproximation are obtained. The attempts to estimate or calculate themodulus
can be a very intricateproblem. 相似文献
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D. Costarelli & R. Spigler 《分析论及其应用》2013,29(2):169-196
In this paper, a constructive theory is developed for approximating functions of one or more variables by superposition of sigmoidal functions. This is done in the uniform norm as well as in the $L^p$ norm. Results for the simultaneous approximation, with the same order of accuracy, of a function and its derivatives (whenever these exist), are obtained. The relation with neural networks and radial basis functions approximations is discussed. Numerical examples are given for the purpose of illustration. 相似文献
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Conditions are studied under which the contribution of the singular part of a measure to the (1,p)-capacity of an arbitrary condenser is zero. 相似文献