修正高阶Hermite插值及Hermite-Fejer插值在Lpw空间中逼近的正逆定理

在LPW空间中引入了一种K-泛函并由此建立了一种以第一类Chebyshev多项式的零点为结点的三种修正高阶Hermite-Fejer插值多项式及一种修正的高阶Hermite插值多项式在LPW空间中逼近的正逆定理.文中的结果说明,对于这几种修正高阶多项式插值的逼近问题而言,正定理的解决意味着逆定理的解决.     

修正高阶Hermite插值及Hermite-Fejer插值在L_ω～p空间中逼近的正逆定理(英文)

在L_ω～p空间中引入了一种 K-泛函并由此建立了一种以第一类 Chebyshev多项式的零点为结点的三种修正高阶 Hermite-Fejer插值多项式及一种修正的高阶 Hermite插值多项式在L_ω～p空间中逼近的正逆定理. 文中的结果说明,对于这几种修正高阶多项式插值的逼近问题而言,正定理的解决意味着逆定理的解决.     

Direct and Inverse Sobolev Error Estimates for Scattered Data Interpolation via Spherical Basis Functions

The purpose of this paper is to get error estimates for spherical basis function (SBF) interpolation and approximation for target functions in Sobolev spaces less smooth than the SBFs, and to show that the rates achieved are, in a sense, best possible. In addition, we establish a Bernstein-type theorem, where the smallest separation between data sites plays the role of a Nyquist frequency. We then use these Berstein-type estimates to derive inverse estimates for interpolation via SBFs.     

Inverses for a class of banded matrices and applications to piecewise cubic approximation

We give a simple criterion for the invertibility of a class of banded matrices that arise in the approximation by piecewise cubic polynomials. We also give a formula for the inverse in terms of the powers of a 2 × 2 matrix. We present sample applications of these results to interpolation and eigenvalue problems. As a side result wee find that the Gaussian points are best.     

Scattered data quasi‐interpolation on spheres

This paper studies the construction and approximation of quasi‐interpolation for spherical scattered data. First of all, a kind of quasi‐interpolation operator with Gaussian kernel is constructed to approximate the spherical function, and two Jackson type theorems are established. Second, the classical Shepard operator is extended from Euclidean space to the unit sphere, and the error of approximation by the spherical Shepard operator is estimated. Finally, the compact supported kernel is used to construct quasi‐interpolation operator for fitting spherical scattered data, where the spherical modulus of continuity and separation distance of scattered sampling points are employed as the measurements of approximation error. Copyright © 2014 John Wiley & Sons, Ltd.     

GLOBAL APPROXIMATION FOR A CLASS OF GENERALIZED MIXED EXPONENTIAL TYPE INTEGRAL OPERATORS IN POLYNOMIAL WEIGHT SPACES

It is shown that a class of generalized mixed exponential type integral operatos on direct theorem of approximation and inverse theorem of approximation hold in CN(I).     

Model checking for partially linear models with missing responses at random

In this paper, we investigate the model checking problem for a partial linear model while some responses are missing at random. By imputation and marginal inverse probability weighted methods, two completed data sets are constructed. Based on the two completed data sets, we build two empirical process-based tests for examining the adequacy of partial linearity of the model. The asymptotic distributions of the test statistics under the null hypothesis and local alternative hypotheses are obtained respectively. A re-sampling approach is applied to obtain the approximation to the null distributions of the test statistics. Simulation results show that the proposed tests work well and both proposed methods have better finite sample properties compared with the complete case (CC) analysis which discards all the subjects with missing data.     

有理反插值

在解决反插值问题时,本文首次利用Thiele型连分式有理插值,得到了两种十分有效的方法:函数插值的有理反插法和反函数的有理插值法,同多项式反插值相比有较好的效果.数值例子说明了在解代数方程时有理反插法优于多项式反插法.     

距离空间中插值神经网络的误差估计

研究距离空间中的神经网络插值与逼近问题.首先引进一类广义的激活函数,用比较简洁的方法讨论距离空间中插值神经网络的存在性,然后给出插值神经网络逼近连续函数的误差估计.     

Approximation with interpolatory constraints

Given a triangular array of points on satisfying certain minimal separation conditions, a classical theorem of Szabados asserts the existence of polynomial operators that provide interpolation at these points as well as a near-optimal degree of approximation for arbitrary continuous functions on the interval. This paper provides a simple, functional-analytic proof of this fact. This abstract technique also leads to similar results in general situations where an analogue of the classical Jackson-type theorem holds. In particular, it allows one to obtain simultaneous interpolation and a near-optimal degree of approximation by neural networks on a cube, radial-basis functions on a torus, and Gaussian networks on Euclidean space. These ideas are illustrated by a discussion of simultaneous approximation and interpolation by polynomials and also by zonal-function networks on the unit sphere in Euclidean space.

     

Spherical Scattered Data Quasi-interpolation by Gaussian Radial Basis Function

Since the spherical Gaussian radial function is strictly positive definite, the authors use the linear combinations of translations of the Gaussian kernel to interpolate the scattered data on spheres in this article. Seeing that target functions are usually outside the native spaces, and that one has to solve a large scaled system of linear equations to obtain combinatorial coefficients of interpolant functions, the authors first probe into some problems about interpolation with Gaussian radial functions. Then they construct quasiinterpolation operators by Gaussian radial function, and get the degrees of approximation. Moreover, they show the error relations between quasi-interpolation and interpolation when they have the same basis functions. Finally, the authors discuss the construction and approximation of the quasi-interpolant with a local support function.     

Inverse and saturation theorems for radial basis function interpolation

While direct theorems for interpolation with radial basis functions are intensively investigated, little is known about inverse theorems so far. This paper deals with both inverse and saturation theorems. For an inverse theorem we especially show that a function that can be approximated sufficiently fast must belong to the native space of the basis function in use. In case of thin plate spline interpolation we also give certain saturation theorems.

     

二元Lagrange三角插值多项式在Orlicz空间内的逼近

研究了二元函数用一种组合型的三角插值多项式算子逼近的问题.借助连续模这一工具,给出了这类三角插值多项式在Orlicz空间内的逼近定理.     

Bounds for a class of linear functionals with applications to Hermite interpolation

A general estimation theorem is given for a class of linear functionals on Sobolev spaces. The functionals considered are those which annihilate certain classes of polynomials. An interpolation scheme of Hermite type is defined inN-dimensions and the accuracy in approximation is bounded by means of the above mentioned theorem. In one and two dimensions our schemes reduce to the usual ones, however our estimates in two dimensions are new in that they involve only the pure partial derivatives.This research was supported in part by the National Science Foundation under grant number N.S.F.-G.P.-9467.     

On the cardinal spline interpolation corresponding to infinite order differential operators

This paper discusses some problems on the cardinal spline interpolation corresponding to infinite order differential operators. The remainder formulas and a dual theorem are established for some convolution classes, where the kernels arePF densities. Moreover, the exact error of approximation of a convolution class with interpolation cardinal splines is determined. The exact values of averagen-Kolmogorov widths are obtained for the convolution class. Supported in part by NSFC.     

单纯形上的Stancu多项式与最佳多项式逼近

作为Bernstein多项式的推广,本文定义单纯形上的多元Stancu多项式.以最佳多项式逼近为度量,建立Stancu多项式对连续函数的逼近定理与逼近阶估计,给出Stancu多项式的一个逼近逆定理,从而用最佳多项式逼近刻划Stancu多项式的逼近特征.     

Nonlinear Approximation and Muckenhoupt Weights

In the general atomic setting of an unconditional basis in a (quasi-) Banach space, we show that representing the spaces of m-terms approximation as Lorentz spaces is equivalent to the verification of two inequalities (Jackson and Bernstein), and that the validity of these two properties is equivalent to the Temlyakov property. The proof is very direct and, especially, does not use interpolation theory. We apply this result to establish a representation theorem when the norm of the (quasi-) Banach space is given by a quadratic variation formula (thanks to a condition called the p-reverse inequality). This quadratic variation framework is in fact very rich and contains, as examples, the cases of Hardy spaces. We also consider the cases of "weighted" Hardy and Lebesgue spaces when the weight belongs to a Muckenhoupt class and the basis is a wavelet basis. This provides a new example of bases well adapted to approximation.     

Approximation of Some Gaussian Processes

We study a class of processes which have a moving average representation with respect to a fixed driving martingale, and can be represented as a mixture of semi-martingale processes. When the driving martingale is Gaussian we obtain a numerically efficient approximation scheme and a central limit theorem (a typical process in this class is fractional Brownian motion).     

The inverse interpolation problem for operators

The inverse problem for a real interpolation functor in the class of ideal spaces is discussed. The most complete solution is obtained for consistent interpolation couples. It follows from the theorems proved in this article and from the concepts introduced that the Marcinkiewicz theorem on interpolation of weak type operators cannot essentially be strengthened.Translated fromMatematicheskie Zametki, Vol. 59, No. 3, pp. 323–333, May, 1996.