ON THE GENERALIZED INVERSE NEVILLE—TYPE MATRIX—VALUED RATIONAL INTERPOLANTS

A new kind of matrix-valued rational interpolants is recursively established by means of generalized Samelson iverse for matrices,with scalar numerator and matrix-valued denominatror.In this respect,it is essentially different form that of the previous works [7,9],where the matrix-valued rational interpolants is in Thiele-type continued fraction form with matrix-valued numerator and scalar denominator.For both univariate and bivariate cases,sufficient conditions for existence,characterisation and univquenese in some sense are proved respectively,and an error formula for the univariate interpolating function is also given.The results obtained in this paper are illustrated with some numerical examples.     

MATRIX ALGORITHMS AND ERROR FORMULA FOR BIVARIATE THIELE-TYPE RECTANGULAR MATRIX VALUED RATIONAL INTERPOLATION

A new method for the construction of bivariate matrix valued rational interpolants (BGIRI) on a rectangular grid is presented in [6]. The rational interpolants are of Thiele-type continued fraction form with scalar denominator. The generalized inverse introduced by [3]is gen-eralized to rectangular matrix case in this paper. An exact error formula for interpolation is ob-tained, which is an extension in matrix form of bivariate scalar and vector valued rational interpola-tion discussed by Siemaszko[l2] and by Gu Chuangqing [7] respectively. By defining row and col-umn-transformation in the sense of the partial inverted differences for matrices, two type matrix algorithms are established to construct corresponding two different BGIRI, which hold for the vec-tor case and the scalar case.     

The compass (star) identity for vector-valued rational interpolants

The compass identity (Wynn's five point star identity) for Padé approximants connects neighbouring elements called N, S, E, W and C in the Padé table. Its form has been extended to the cases of rational interpolation of ordinary (scalar) data and interpolation of vector-valued data. In this paper, full specifications of the associated five point identity for the scalar denominator polynomials and the vector numerator polynomials of the vector-valued rational interpolants on real data points are given, as well as the related generalisations of Frobenius' identities. Unique minimal forms of the polynomials constituting the interpolants and results about unattainable points correspond closely to their counterparts in the scalar case. This revised version was published online in June 2006 with corrections to the Cover Date.     

二元向量值有理插值存在性的一种判别方法

文章给出了对于矩形网格上基于二元Newton插值公式的二元向量值有理插值存在性的充要条件.在存在的情况下,建立了具有显式表达式的不同于向量连分式的二元向量值有理插值函数,并且这种方法具有承袭性.最后给出的实例说明了这种算法的有效性.     

BIVARIATE LAGRANGE-TYPE VECTOR VALUED RATIONAL INTERPOLANTS

1. IntroductionWynn [11] proposed a method for rational interpolation of vector-vaued quantities givenon a set of distinct illterpolation points. He used colltinued fractions and generalized inversesfor the reciproca1 of vector-vaued qualltities. McCleod …     

矩形网格上二元NEVILLE型向量有理插值

A new kind of bivariate vector-valued rational interpolants is recursively established by means of Samelson inverse over rectangular grids, with scalar numerator and vector-valued denominator. In this respect, it is essentially different from that of the previous work. Sufficient conditions for existence, characterization and uniqueness in some sense are proved respectively. And the resIuts in the paper are illustrated with some numerical examples.     

Bivariate Thiele-type matrix-valued rational interpolants

A new method for the construction of bivariate matrix-valued rational interpolants on a rectangular grid is introduced in this paper. The rational interpolants are of the continued fraction form, with scalar denominator. In this respect the approach is essentially different from that of Bose and Basu (1980) where a rational matrix-valued approximant with matrix-valued numerator and denominator is used for the approximation of a bivariate matrix power series. The matrix quotients are based on the generalized inverse for a matrix introduced by Gu Chuanqing and Chen Zhibing (1995) which is found to be effective in continued fraction interpolation. A sufficient condition of existence is obtained. Some important conclusions such as characterisation and uniqueness are proven respectfully. The inner connection between two type interpolating functions is investigated. Some examples are given so as to illustrate the results in the paper.     

Lagrange基函数的复矩阵有理插值及连分式插值

1引言 矩阵有理插值问题与系统线性理论中的模型简化问题和部分实现问题有着紧密的联系~[1][2]，在矩阵外推方法中也常常涉及线性或有理矩阵插值问题~[3]。按照文~[1]的阐述。目前已经研究的矩阵有理插值问题包括矩阵幂级数和Newton-Pade逼近。Hade逼近，联立Pade逼近，M-Pade逼近，多点Pade逼近等。显然，上述各种形式的矩阵Pade逼上梁山近是矩     

矩形网格上二元向量有理插值的对偶性

矩形网格上二元向量有理插值的对偶性朱功勤，檀结庆（合肥工业大学）ＴＨＥＤＵＡＬＩＴＹＯＦＢＩＶＳＲＩＡＴＥＶＥＣＴＯＲＶＡＬＵＥＤＲＡＴＩＯＮＡＬＩＮＴＥＲＰＯＬＡＮＴＳＯＶＥＲＲＥＣＴＡＮＧＵＬＡＲＧＲＩＤＳ￥ＺｈｕＧｏｎｇ－ｑｉｎ；ＴａｎＪｉｅ－...     

二元对角向量值有理插值的算法

首先提出了二元对角向量值有理插值问题,它包括主对角和副对角两种向量值有理插值,并分别给出了主对角线和副对角线上向量值有理插值的两种算法,即直接求系数bi,j的算法和基于Samelson广义逆所定义的特殊初等变换的矩阵算法.然后构造了在预给极点情况下求主对角线和副对角线上向量值有理插值的矩阵算法.最后给出多个数值例子说明上述算法的有效性.     

构造二元向量值有理插值函数的一种新方法

At present, the methods of constructing vector valued rational interpolation function in rectangular mesh are mainly presented by means of the branched continued fractions. In order to get vector valued rational interpolation function with lower degree and better approximation effect, the paper divides rectangular mesh into pieces by choosing nonnegative integer parameters d1 （0 〈 dl ≤ m） and d2 （0 ≤ d2≤ n）, builds bivariate polynomial vector interpolation for each piece, then combines with them properly. As compared with previous methods, the new method given by this paper is easy to compute and the degree for the interpolants is lower.     

ALGORITHMS FOR LACUNARY VECTOR VALUED RATIONAL INTERPOLANTS

Efficient algorithms are established for the computation of bivariate lacunary vector valued rational interpolants based on the branched continued fractions and a numerical example is given to show how the algorithms are implemented,     

向量值有理插值存在性的一种判别方法

对于向量值有理插值的计算,目前已经有多种求解算法.但其存在性的判别方法及其证明在现有的文献中还没有见到.这里利用标量有理插值函数插值存在性的思想,引入Newton基函数,给出并证明了向量值有理插值存在性的一种判别方法.同时给出有理插值函数的分子和分母的显式表达式,最后的实例说明了它的有效性.     

预给极点的向量有理插值及性质

1　引　　言在工程技术中经常会遇到一些多元奇异函数的计算问题,常规的有理插值方法无疑为这类问题的近似求解提供了有效的途径,但有时逼近效果不一定十分理想,其重要原因之一是人们往往采用统一的框架去构造有理插值公式,而忽略了被逼近对象的一些本质特征.针对某些具体问题,例如已知被逼近的向量值函数的奇异点的有关信息,构造一种预给极点的向量有理插值格式就显得很有必要,其逼近效果自然会更理想.设R2中的点集Πn,m={(xi,yj)|i=0,1,…,n;j=0,1,…,m},相应的d维向量集Vn,m={Vi,j∈Cd|i=0,1,…,n;j=0,1,…,m}.设V∈Cd为任一d维…     

二元Thile型向量有理插值的误差公式

借助于Ｓｏｍｅｌｓｏｎ广义逆，文［１］首次讨论了多元向量有理插值问题．本文得到了二元Ｔｈｉｅｌｅ型向量有理插值的一个精确的误差公式．     

BIVARIATE RATIONAL INTERPOLANTS WITHRECTANGLE-HOLE-STRUCTURE

1.IntroductionGivenasetofdistinctrealpoints{xi,i~0,1,2,',n:xiER}andasetofcomplexvectordata{d'),i=0,1,2,',n:n)ECd},Graves-Momsshowed[5]thatthevectorvaluedThieletypecontinuedfractioncanservetointerpolatethegivenvectors.TheconstructionprocessiscloselyralatedtotheadoptionoftheSamelsoninverseforvectorswhere7denotesthecomplexconjugateofvector6.ItwasprovedthatS(x)isavectorvaluedrationalfunctionwithnumeratorbeingad-dimensionalpolynomialofdegreenanddenominatorbeingapolynomialofdegree2[n/2],here…     

Bivariate composite vector valued rational interpolation

In this paper we point out that bivariate vector valued rational interpolants (BVRI) have much to do with the vector-grid to be interpolated. When a vector-grid is well-defined, one can directly design an algorithm to compute the BVRI. However, the algorithm no longer works if a vector-grid is ill-defined. Taking the policy of ``divide and conquer', we define a kind of bivariate composite vector valued rational interpolant and establish the corresponding algorithm. A numerical example shows our algorithm still works even if a vector-grid is ill-defined.

     

COMPUTATION OF VECTOR VALUED BLENDING RATIONAL INTERPOLANTS

As we know, Newton's interpolation polynomial is based on divided differences which can be calculated recursively by the divided-difference scheme while Thiele 's interpolating continued fractions are geared towards determining a rational function which can also be calculated recursively by so-called inverse differences. In this paper, both Newton's interpolation polynomial and Thiele's interpolating continued fractions are incorporated to yield a kind of bivariate vector valued blending rational interpolants by means of the Samelson inverse. Blending differences are introduced to calculate the blending rational interpolants recursively, algorithm and matrix-valued case are discussed and a numerical example is given to illustrate the efficiency of the algorithm.     

VECTOR VALUED RATIONAL INTERPOLANTS BY TRIPLE BRANCHED CONTINUED FRACTIONS

Triple branched continued fractions (TBCFs) are constructed by means of well-define Thiele-type partial inverted differences. The characterizatioon theorem, uniqueness theorem andsome projection identity properties are obtained for vector valued rational interpolants hy TBCFs.     

On a vector q‐d algorithm

Using the framework provided by Clifford algebras, we consider a non‐commutative quotient‐difference algorithm for obtaining the elements of a continued fraction corresponding to a given vector‐valued power series. We demonstrate that these elements are ratios of vectors, which may be calculated with the aid of a cross rule using only vector operations. For vector‐valued meromorphic functions we derive the asymptotic behaviour of these vectors, and hence of the continued fraction elements themselves. The behaviour of these elements is similar to that in the scalar case, while the vectors are linked with the residues of the given function. In the particular case of vector power series arising from matrix iteration the new algorithm amounts to a generalisation of the power method to sub‐dominant eigenvalues, and their eigenvectors. This revised version was published online in June 2006 with corrections to the Cover Date.