长方体网格上的三元连分式的插值

本文利用递推公式构造了一个空间长方体网格上的三元连分式的插值公式,插值的存在性和唯一性得到了证明,一个数例说明了插值方法的有效性。     

基于二元连分式的散乱数据递推插值格式

本文首先基于新的非张量积型偏逆差商递推算法,分别构造奇数与偶数个插值节点上的二元连分式散乱数据插值格式,进而得到被插函数与二元连分式间的恒等式.接着,利用连分式三项递推关系式,提出特征定理来研究插值连分式的分子分母次数.然后,数值算例表明新的递推格式可行有效,同时,通过比较二元Thiele型插值连分式的分子分母次数,发现新的二元插值连分式的分子分母次数较低,这主要归功于节省了冗余的插值节点. 最后,计算此有理函数插值所需要的四则运算次数少于计算径向基函数插值.     

二元插值的一般框架

本文通过引进多参数建立了二元插值的一般框架.这样,许多著名的经典插值格式,如Newton插值、分叉连分式插值、对称连分式插值等均可视为本文的特殊情形．     

Stieltjes-Newton型有理插值

Stieltjes型分叉连分式在有理插值问题中有着重要的地位，它通过定义反差商和混合反差商构造给定结点上的二元有理函数，我们将Stieltjes型分叉连分式与二元多项式结合起来，构造Stieltje- Newton型有理插值函数，通过定义差商和混合反差商，建立递推算法，构造的Stieltjes-Newton型有理插值函数满足有理插值问题中所给的插值条件，并给出了插值的特征定理及其证明，最后给出的数值例子，验证了所给算法的有效性．     

样条空间S^13（Δ^（1）mn）上的插值与逼近

本文讨论样条空间Ｓ＾１３上的插值问题，导出了一类插值条件下样条插值的存在性与唯一性结论以及计算插值样条的递推格式，其主要结论是对四阶光滑的函数，插值样条可达２阶逼近度。     

一个二元矩阵插值连分式的展开式

本文借助于文[1]定义的一种实用的矩阵广义逆,构造了一个二元Stieltjes型矩阵值插值连分式的展开式,它的截断分式可以定义二元矩阵值插值函数.     

连幂式插值

根据连续幂指形式的函数,提出了连续幂指形式的函数插值的概念,简称连幂式插值,用构造式方法得到了满足插值条件的连幂式插值函数。最后,通过一个算例与连分式插值函数做了对比。     

关于Newton—Thiele型二元有理插值的存在性问题

基于均差的牛顿插值多项式可以递归地实现对待插值函数的多项式逼近,而Thiele型插值连分式可以构造给定节点上的有理函数。将两者结合可以得到Newton-Thiele型二元有理插值（NTRI）算法,本文解决了NTRI算法的存在性问题,并有数值例子加以说明。     

一种保形C~1三次样条插值方法

本文得到了构造一个保形Ｃ１三次插值样条函数的充要条件，并给出了一种构造保形Ｃ１三次插值样条函数的方法．     

C~k连续的保形分段2k次多项式插值

1．引言在每个子区间上，通过插入至多一个内结点，Brodlie和Butt［1］给出了分段三次多项式保形插值算法，Randal［2］等讨论了分段五次多项式插值，作者［31讨论了一般分段奇次多项式的保形插值，并且给1了内结点的位置范围公式．这种插值方法完全解决了一般的分段奇次多项式的保形插值问题．关于分段偶次多项式的保形插值，大多数文献只讨论分段二次保形插值，这里要特别指出的是Shumake［4j导出了二次样条保凸的充要条件，并且给出了一个二次样条保形插值的方法．在每一个子区间上至多插入一个内结点，则一个二次插值样条就可得到．作…     

凸四边形上一类具有C~2-连续的插值问题的样条解及其应用

本文讨论了一类凸四边形上的插值问题.指出这类插值问题是可解的,其解是分片二元三次多项式,且在凸四边形上是C~2-连续的.我们证明了这类插值问题的解的存在性和唯一性,给出了解样条的分片表达式及其逼近度的估计.最后还给出了一个应用实例和图形显示来说明本方法是可行的.     

On Optimal Error Bounds for Derivatives of Interpolating Splines on a Uniform Partition

Based on Peano kernel technique, explicit error bounds (optimal for the highest order derivative) are proved for the derivatives of cardinal spline interpolation (interpolating at the knots for odd degree splines and at the midpoints between two knots for even degree splines). The results are based on a new representation of the Peano kernels and on a thorough investigation of their zero distributions. The bounds are given in terms of Euler–Frobenius polynomials and their zeros.     

Local Lagrange Interpolation with Bivariate Splines of Arbitrary Smoothness

We describe a method which can be used to interpolate function values at a set of scattered points in a planar domain using bivariate polynomial splines of any prescribed smoothness. The method starts with an arbitrary given triangulation of the data points, and involves refining some of the triangles with Clough-Tocher splits. The construction of the interpolating splines requires some additional function values at selected points in the domain, but no derivatives are needed at any point. Given n data points and a corresponding initial triangulation, the interpolating spline can be computed in just O(n) operations. The interpolation method is local and stable, and provides optimal order approximation of smooth functions.     

Pseudo-polyharmonic vectorial approximation for div-curl and elastic semi-norms

Vector field reconstruction is a problem arising in many scientific applications. In this paper, we study a div-curl approximation of vector fields by pseudo-polyharmonic splines. This leads to the variational smoothing and interpolating spline problems with minimization of an energy involving the curl and the divergence of the vector field. The relationship between the div-curl energy and elastic energy is established. Some examples are given to illustrate the effectiveness of our approach for a vector field reconstruction.     

一类带参数的有理三次三角Hermite插值样条

给出一种带有参数的有理三次三角Hermite插值样条,具有标准三次Hermite插值样条相似的性质.利用参数的不同取值不但可以调控插值曲线的形状,而且比标准三次Hermite插值样条更好地逼近被插曲线.此外,选择合适的控制点,该种插值样条可以精确表示星形线和四叶玫瑰线等超越曲线.     

Bivariate interpolating polynomials and splines (I)

The multivariate splines which were first presented by de Boor as a complete theoretical system have intrigued many mathematicians who have devoted many works in this field which is still in the process of development. The author of this paper is interested in the area of interpolation with special emphasis on the interpolation methods and their approximation orders. But such B-splines (both univariate and multivariate) do not interpolated directly, so I approached this problem in another way which is to extend my interpolating spline of degree 2n-1 in univariate case (See[7]) to multivariate case. I selected triangulated region which is inspired by other mathematician’s works (e.g. [2] and [3]) and extend the interpolating polynomials from univariate to m-variate case (See [10])In this paper some results in the case m=2 are discussed and proved in more concrete details. Based on these polynomials, the interpolating splines (it is defined by me as piecewise polynomials in which the unknown partial derivatives are determined under certain continuous conditions) are also discussed. The approximation orders of interpolating polynomials and of cubic interpolating splines are inverstigated. We limited our discussion on the rectangular domain which is partitioned into equal right triangles. As to the case in which the rectangular domain is partitioned into unequal right triangles as well as the case of more complicated domains, we will discuss in the next paper.     

The bidimensional interproximation problem and mixed splines

Interproximation methods for surfaces can be used to construct a smooth surface interpolating some data points and passing through specified regions. In this paper we study the use of mixed splines, that is smoothing splines with additional interpolation constraints, to solve the interproximation problem for surfaces in the case of scattered data. The solution is obtained by solving a linear system whose structure can be improved by using “bell-shaped” thin plate splines.     

An interpolation method by bivariate cubic splines with <Emphasis Type="Italic">c</Emphasis><Superscript>2</Superscript>-join on type-II triangulars at a rectangular domain

In this paper, an interpolating method for bivariate cubic splines with C ²-join on type-II triangular at a rectangular domain is given, and the approximation degree, interpolating existence and uniqueness of the cubic splines are studied. Supported by NSFC General Projects(60473130).     

(Ⅱ)型三角剖分下带边界条件的二元二次样条插值

本文研究(Ⅱ)型三角剖分下带边界条件的二元二次样条插值问题的存在唯一性与插值节点分布的关系,并且在证明了中心插值、角点插值和偏心插值问题解的存在唯一性的基础上,给出了这三种插值函数的构造方法.