Extended convergence regions for the AOR method

In this paper, we give sufficient conditions for the convergence of the (AOR) method, when the matrix A for Ax = b is a strictly diagonally dominant matrix. These results improve the conclusions obtained in the Theorem 4 [10].With the notion of generalized diagonal dominant matrix, we enlarge the convergence regions given in Theorem 9 [10], when A is a nonsingular H-matrix.In the last section we generalize theorem 6 of Robert [11] and we present some results which extend the convergence regions for the (AOR) method.     

AOR方法的收敛性定理

获得了著名的AOR方法收敛的实用条件和H矩阵的实用判别条件。所得AOR方法的收敛条件便于实际计算应用,适用范围不要求方程组系数矩阵对角占优,适用于数学物理问题中广泛的矩阵类。给出的数值例子表明了所得结果的实用性。     

区间AOR方法的收敛性

设A∈I(R~(n×n)是一个区间矩阵,b∈I(R~n)是区间向量.将A分解成 A=D-L-U,其中D,-L和-U分别是A的对角矩阵、严格下和上三角矩阵.假定A的每个对角元均不为零,则可引进求解区间线性方程组     

On the convergence of multi-grid methods with transforming smoothers

Summary In the present paper we give a convergence theory for multi-grid methods with transforming smoothers as introduced in [31] applied to a general system of partial differential equations. The theory follows Hackbusch's approach for scalar pde and allows a convergence proof for some well-known multi-grid methods for Stokes- and Navier-Stokes equations as DGS by Brandt-Dinar, [5], TILU from [31] and the SIMPLE-methods by Patankar-Spalding, [23].This work was supported in part by Deutsche Forschungsgemeinschaft     

某些广义迭代法的Stein－Rosenberg型定理与比较定理

某些广义迭代法的Ｓｔｅｉｎ－Ｒｏｓｅｎｂｅｒｇ型定理与比较定理王新民（中国金融学院）ＳＴＥＩＷ－ＲＯＳＥＮＢＥＲＧＴＹＰＥＴＨＥＯＲＳＭＳＡＮＤＣＯＭＭＭＳＯＮＴＨＥＯＲＥＭＳＦＯＲＳＯＭＥＧＥＮＥＲＡＬＩＺＥＤＩＴＥＲＡＩＶＥＭＥＴＨＯＤＳ￥Ｗａｎ...     

A one parameter method for the matrix inverse square root

This paper is motivated by the paper [3], where an iterative method for the computation of a matrix inverse square root was considered. We suggest a generalization of the method in [3]. We give some sufficient conditions for the convergence of this method, and its numerical stabillity property is investigated. Numerical examples showing that sometimes our generalization converges faster than the methods in [3] are presented.     

非奇H-矩阵的实用判别准则

非奇H-矩阵在科学和工程实际中有着广泛地应用,但在实际中判定一个矩阵是否为非奇H-矩阵是比较困难的.通过构造不同的正对角阵,结合不等式的放缩技巧,给出了一些比较实用的新条件,改进和推广了现有的一些结论,并给出相应的一些数值算例来说明结果的有效性.     

Convergence of generalized AOR iterative method for linear systems with strictly diagonally dominant matrices

In this paper, some improvements on Darvishi and Hessari [On convergence of the generalized AOR method for linear systems with diagonally dominant coefficient matrices, Appl. Math. Comput. 176 (2006) 128–133] are presented for bounds of the spectral radius of _lω,r$l_{\omega ,r}$, which is the iterative matrix of the generalized AOR (GAOR) method. Subsequently, some new sufficient conditions for convergence of GAOR method will be given, which improve some results of Darvishi and Hessari [On convergence of the generalized AOR method for linear systems with diagonally dominant coefficient matrices, Appl. Math. Comput. 176 (2006) 128–133].     

Strong convergence of iterative methods for k-strictly pseudo-contractive mappings in Hilbert spaces

In this paper, we introduce composite iterative schemes for finding fixed points of k-strictly pseudo-contractive mappings for some 0?k<1 in Hilbert spaces. Then, under certain different control conditions, we establish strong convergence theorems on the composite iterative schemes. The main theorems improve and generalize the recent corresponding results of Cho et al. [5] and Marino and Xu [9] as well as Halpern [6], Wittmann [12], Moudafi [10] and Xu [14].     

AOR方法的收敛性

A.Hadjidimos在[1]中提出一个迭代求解线性方程组的 AOR方法(Accelerated Overre-laxation Method),并在方程组的系数矩阵为不可约弱对角优势、L-矩阵和相容有序矩阵的条件下,讨论了此方法的收敛性.在这篇文章里,我们将考虑系数矩阵是H-矩阵、正定矩阵以及L-矩阵的情况.所得结果表明,可以放宽在[1]的3,4两节中对参数所加的限制.     

Majorizing functions and two-point Newton-type methods

The semi-local convergence of a Newton-type method used to solve nonlinear equations in a Banach space is studied. We also give, as two important applications, convergence analyses of two classes of two-point Newton-type methods including a method mentioned in [5] and the midpoint method studied in [1], [2] and [12]. Recently, interest has been shown in such methods [3] and [4].     

一类非单调算法的收敛性质

1.搜索步长和搜索方向对于无约束最优化问题(?)f(x),其中f:R~n→R~1,f∈C~1,一般采用形如x_(k+1)=x_k+λ_kd_k(k=1,2,…)的迭代算法来求解,这里λ_k为搜索步长,d_k为搜索方向.     

On the stability of the incomplete LU-factorizations and characterizations of H-matrices

Summary. Meijerink and van der Vorst [8] have shown that the incomplete LU-factorizations are numerically stable for M-matrices. Varga, Saff and Mehrmann [16] gave some characterizations of the H-matrices by using the incomplete LU-factorizations of them. The purpose of this paper is to show that the incomplete LU-factorizations of an H-matrix are at least as stable as the complete LU-factorizations of its comparison matrix. We give also some new characterizations of the H-matrices in connection with their incomplete LU-factorizations. Received November 12, 1993 / Revised version received May 27, 1994     

非奇异H-矩阵的实用判定

H-矩阵在许多领域中都起着非常重要的作用,例如数学分析、矩阵理论、数学经济学、控制论等.但是在实际运用中判定H-矩阵却十分困难.本文类似于文[4],均以α-对角占优理论为基础,给出H-矩阵的若干实用判定,改进了文[3]的相应结果.     

A Spectral Method for a Class of Nonlinear Quasi-Parabolic Equations

1.IntroductionThispaperconsidersthefollowingnonlinearquasi-parabolicequationsofhigherorderwithperiodicboundaryconditions:Here,u(x,t)isavectorfunctionwithdimensionJu(x,t)=(u1(x,t),...9uJ(x,t)),A=(ai,j)ij=,isasymmetricandpositivedefinitematrix,andaijarerealconstants,i.e.(1)takesthefo1lowingform:werehj(u)isafunctionofthevectorultheJacobimatrixofh=(hj)j,issemi-bounded,i'e.thereexistsaconstantbsuchthatASpectralMeth0df0raClass('f\,)11li1l`..1r()llJsiIJaraI)')licI:q11ati(f)lls89F=F(PO,...iPM-l…     

A new method for solving a class of mixed boundary value problems with singular coefficient

In [1], [2], [3], [4], [5], [6] and [7], it is very difficult to deal with initial boundary value conditions. In this paper, we give a new method to deal with boundary value conditions, the main contribution of this paper is to put mixed boundary value conditions into reproducing kernel Hilbert space. The numerical examples are studied to demonstrate the accuracy of the present method. Results obtained by the method indicate the method is simple and effective.     

A unifying theorem for Newton’s method on spaces with a convergence structure

We present a semilocal convergence theorem for Newton’s method (NM) on spaces with a convergence structure. Using our new idea of recurrent functions, we provide a tighter analysis, with weaker hypotheses than before and with the same computational cost as for Argyros (1996, 1997, 1997, 2007) [1], [2], [3] and [5], Meyer (1984, 1987, 1992) [13], [14] and [15]. Numerical examples are provided for solving equations in cases not covered before.     

Reliability bounds for NBUE and NWUE distributions

In [5], many inequalities for NBUE and NWUE life distributions are given. But, since there are some basic observations which do not hold (see Section 1 for details), many results obtained in [5] are not true. In this note we propose some remedies and give some new results.The proect supported by the National Natural Science Foundation of China.     

A Modified SQP Method and Its Global Convergence

The sequential quadratic programming method developed by Wilson, Han andPowell may fail if the quadratic programming subproblems become infeasibleor if the associated sequence of search directions is unbounded. In [1], Hanand Burke give a modification to this method wherein the QP subproblem isaltered in a way which guarantees that the associated constraint region isnonempty and for which a robust convergence theory is established. In thispaper, we give a modification to the QP subproblem and provide a modifiedSQP method. Under some conditions, we prove that the algorithm eitherterminates at a Kuhn–Tucker point within finite steps or generates aninfinite sequence whose every cluster is a Kuhn–Tucker point.Finally, we give some numerical examples.     

A note on a consistent estimator of a mixing distribution function

Summary In this note, we will study a consistent estimator of a mixing distribution function (mixing d.f.). The estimator discussed in this note is that of Choi and Bulgren [4]. Since there is some doubt about the way of proving Lemma in [4] which is used for showing the consistency of the estimator in [2], [3] and [4], we will give different lemmas. We will show that their result (which is still true by using our lemmas) holds under a weaker assumption than theirs. The existence of the estimator is not discussed in [4]. So, we will give conditions under which the existence is guaranteed. The research was supported in part by Scientific Research Fund from the Ministry of Education of Japan. No. 564076.