用小波限制紧算子逼近奇异积分算子的速度

根据Beylin-Coifman-Rokhlin和Yang的观点，用合适的小波基可以刻画性地研究C.Z算子或拟微分算子，这样就可以用小波来计算算子，比如可以从奇异积分算子的B-C-R算法刻画出发，用小波限制紧算子进行逼近，本文旨在计算作为原算子与逼近算子的差的误差算子的H1到L1的连续性范数的最佳衰减速度和在Lp上的连续性范数的衰减速度的范围。     

Hermite插值算子在Orlicz空间内的逼近

插值算子逼近是逼近论中一个非常有趣的问题,尤其是以一些特殊的点为结点的插值算子的逼近问题很受人们的关注.研究了以第一类Chebyshev多项式零点为插值结点的Hermite插值算子在Orlicz范数下的逼近.     

Simultaneous Interpolation and Approximation by a Class of Multivariate Positive Operators

The purpose of this paper is to show that the interpolation positive operators of a wide class satisfy also the approximation property. Such a situation of simultaneous interpolation and approximation may be very desirable, but is rather unusual. Our attention is focused on the convergence problem, giving the conditions under which a sequence of operators of the considered class converges to a continuous function in a convex compact set in R ^m (m∈N). It must be recalled that many of these operators are very interesting in applications and that suitable algorithms can be devised for parallel, multistage and iterative computation.     

积分型Meyer-K?nig-Zeller算子的逼近性质

本文讨论了积分型Meyer-K?nig-Zeller算子的逼近度和饱和性质.所得结论表明,积分型Meyer-K?nig-Zeller算子和Kantorovich型Meyer-K?nig-Zeller算子有相同的逼近阶、饱和阶及饱和类.     

Approximation of Hypersingular Integral Operators With Cauchy Kernel

In the present article, the hypersingular integral operator with Cauchy kernel H is approximated by a sequence of operators of a special form, and it is proved that the approximating operators H_n strongly converge to the operator H and for an algebraic polynomial of degree not higher than n the operators H_n and H coincide. Therefore, the estimate established in this article yields more exact results in terms of the convergence rate than traditional methods. At the end we give the approximate solution of the hypersingular integral equation of the first kind.     

Lp空间有理插值型算子的逼近

考虑了两类有理插值型算子的Jackson型估计．当p〉1时．建立了Dilzian—Totik型定理，当p=1时．利用通常连续模给出了Jackson型估计．     

一类修正的和与积分混合型算子的$L_p$逼近

The generalized summation integral type operators with Beta basis functions are widely studied. At present, the investigations for the properties of these operators are only limited to the functions of bounded variation. Some authors studied the rate of point-wise rate of convergence, asymptotic formula of Voronovskaja type, and some direct results about these type of operators. The present paper considers the direct, inverse and equivalence theorems of modified summation integral type operators in the Lp spaces.     

Approximation of Infinitely Differentiable Periodic Functions by Interpolation Trigonometric Polynomials in Integral Metric

We obtain asymptotic equalities for the upper bounds of approximations of periodic infinitely differentiable functions by interpolation trigonometric polynomials in the metric of L₁ on the classes of convolutions.     

Bernstein算子的逼近

本文利用点态光滑模ωφλ2r(f,t)研究了Bernstein算子的r阶线性组合的点态逼近.当1-1/r≤λ≤1时,用ωφλ2r(f,t)给出了—个点态逼近等价定理.且用反例说明了当0≤λ<1-1/r 时,此结论不成立.但若限制0<αφλ2r(f,t)给出     

The Integral Type Modification of Jain Operators and its Approximation Properties

Abstract

In the present paper, we discuss the approximation properties of Durrmeyer-Stancu type variant of Jain operators with the modified forms of the Beta basis functions. We establish some direct results, which include the asymptotic formula, the error estimation in terms of the modulus of continuity and weighted approximation. Also, we construct a King modification of these operators which preserves the test functions e₀ and e₁.     

一类插值多项式算子与无界函数逼近

将经典“试探函数组”1,x,x^2应用于扩展乘数法,建立了一个判别线性正算子能否改造为逼近任何无界连续函数的充要条件。利用该条件给出了一类变形的插值多项式算子的收敛性定理,得到了具有一般性的结论。     

三阶Hermite插值算子在Orlicz空间内的加权逼近

研究了修正的加权三阶Hermite插值算子在Orlicz空间的逼近性质,利用加权连续模、HardyLittlewood极大函数、Hlder不等式等工具给出了该插值算子在Orlicz空间内的逼近度估计.     

Shepard-Lagrange算子的逼近

本文建立了Shepard-Lagrange算子逼近的正逆定理,证明了可以利用高阶光滑模来刻画Shepard-Lagrange算子的逼近性质.从而说明了Shepard-Lagrange算子比一般的Shepard算子具有更好的逼近性质.进一步,所用光滑模的阶梯函数非常广泛,这是多项式逼近所不具有的.     

Approximation by Multivariate Bernstein Operators

The best lower and upper estimates for the multivariate Bernstein operators on a simplex or a cube are achieved. Crucial in our approach are estimates for the partial derivative of iterated multivariate Bernstein operators.     

关于Baskakov－Kurrmeyer算子的一致逼近

本文首先给出了Ｂａｓｋａｋｏｖ－Ｄｕｒｒｍｅｙｅｒ算子在一致副近意义下的正定理，并把它推广到一类线性组合的情形，然后讨论了它的导数与光滑模的等价关系，最后给出了二元Ｂａｓｋａｋｏｖ－Ｄｕｒｒｍｅｙｅｒ算子逼近阶的特征刻画．     

Weighted Approximation by Rational Operators

The author constructs rational operators for the weighted uniform approximation of functions with endpoints singularities by algebraic weights in [?1,1]. New direct and converse results not possible by polynomials are proved.     

球面卷积算子逼近

研究d维欧氏空间R~d中单位球面上卷积算子的逼近问题.利用球面乘子理论以及K-泛函与光滑模等价关系,建立一类球面卷积算子逼近的正、逆定理.特别地,给出了逼近的强型逆向不等式,从而揭示了该类球面卷积算子的本质逼近阶.此外,作为应用,给出了球面Jackson-Matsuoka卷积算子与Abel-Poisson卷积算子逼近上、下界的相同阶估计.     

Approximation Properties by q-Durrmeyer-Stancu Operators

In this paper, we are dealing with q-Bemstein-Durrmeyer-Stancu operators. Firstly, we have estimated moments of these operators. Then we have discussed some approximation properties and asymptotic formulas. We have obtained better estimations by using King type approach and given statistical convergence for the operators.