聚类分析是数值分类学的一个分支,在这方面已有系统的研究和总结.近年来Fuzzy聚类分析法引起较广泛的重视,但从实例上看,由于受到人为因素干扰,聚类结果有不同程度的失真现象.为此,文中将动态聚类的基本原理同Fuzzy图连通强度概念

In the present paper, we give a review of pseudo-random number generators. The new methods and theory appearing in 1990's will be focused. This paper concerns with almost all kinds of generators such as the linear, nonlinear and in- versive congruential methods, Fibonacci and Tausworthe (or feedback shift regis- ter) sequences, add-with-carry and subtract-with-borrow methods, multiple prime generator and chaotic mapping, as well as the theory of combination of generators.

有限元法是力学的一个有力工具,目前应用日益广泛,研究工作越来越向深入发展.随着有限元法之后,又产生了有限条法及样条变分法.这些方法,对于规则区域,解题比有限元法方便,而且效率较高,我们在学习这些方法的基础上,发扬优点,改正缺点,提出一个有限点法. 有限点法是以样条函数、梁振动函数(或三角函数)及能量法为基础的,因此又叫样条有限点法.本文主要介绍有限点法的基本原理及计算方法.除特别声明者外,所有符号与常用者同.

This paper presents the Alternating Segment Explicit-Implicit (ASE-I) method forsolving the convection-diffusion equation. The method has the obvious property ofparallelism, and is unconditionally stable. Numerical example is presented.

§ 非负矩阵理论作为一种基本工具,被广泛地应用于数值分析、图论、计算机科学、管理科学等领域中.对非负矩阵最大特征值进行估计,又是该理论的核心问题之一.如果上下界能表示为矩阵元素的易于计算的函数,那么这种估计的价值更高.最著名且用得最多的当算G.Frobenius[1]界值. Frobenius界值定理.设r是n阶非负矩阵A的最大特征值,ri(i=1,2,…,n)为A的i行行和,则 minri≤r≤maxri(1.1) i i 　 对于A的i列列和Ci(i=1,2,…,n),有相同的结论. 对于有非零行和的非负矩阵A,H.Minc[2]把(1.1)式改进为(1.2)

时间序列分析主要有两个目的,一是分析时间序列的统计规律;二是根据过去和现在的观测样本构造拟合序列的最佳数学模型,并用此模型对未来进行预报。其中周期图、功率谱和最大熵谱估计等都是分析时间序列性质的有效工具,但它们本身不能用于对未来的预报。自回归模型(AR)和自回归滑动平均模型(ARMA)建立了描述序列前后相

二次多项式根的大小在差分格式和系统的稳定性判定方面有着重要的意义.这里我们推荐有关的Schur-Cohn定理及其推广Miller定理,并给出初等证明. 考察二次多项式p(z)=az~2+bz+1(a≠0)的根z_1,z_2的模的大小.设z_1=

有限元线法(Pinite Element Method of Lines,简称FEMOL)是一种新型的以常微分方程(Ordinary Differential Equation,简称ODE)求解器(Solver)为支撑软件的半解析方法.在该法中,我们首先利用有限元技术将控制微分方程半离散化为用结线函数表示的常微分方程组(ODEs),然后选用高质量的ODE求解程序直接求解(本文中采用COLSYS),得到满足用户预先指定的误差限的ODE解答,作为原问题的近似解.

Delaunay triangulation has been widely used in many fields such as compu- tational fluid dynamics, statistics, meteorology solid state physics, computational geometry and so on. Bowyer-Watson algorithm is a very popular one for generating Delaunay triangulation. In generating the Delaunay triangulation of a preassigned set of n points, the complexity of Bowyer-Watson algorithm can at most be reduced to O(n log n) for the simple reason that the complexity of its tree search process is O(nlog n). In this paper we suggest a tree search technique whose complexity is O(n). Noting that the order of point insertion can affect the efficiency of Bowyer- Watson algorithm, we propose a technique to optimize the point insertion process. Based on these two techniques, we obtain a fast algorithm for generating Delaunay triangulation.

本文的目的是研究适合在并行机与向量机上求解下述扩散方程的有限差分方法:求满足的解 u(x,t),适合初始条件 u(x,O)=f(x),O≤x≤l (2) 及边界条件 u(0,i)=g_0(t), u(1,t)=g_t(t). (3) 习知,在求解上述问题的有限差分逼近方法中,古典显式方法适合于并行计算,但不绝对稳定、而像古典隐式和Crank-Nicolson格式这类隐式方法是绝对稳定的,但需要求解线性代数方程组,实现并行计算有一定困难。D.J.Evans和 A.R.Abdullah 巧

本文讨论了一类数值求解二维热传导方程的并行差分格式．在这个算法中,通过引进内界点将求解区域分裂成若干子区域．在子区域间内界点上采用非对称格式计算,一旦这些点的值被计算出来,各子区域间的计算可完全并行．本文得到了稳定性条件和最大模误差估计．它表明我们的格式有令人满意的稳定性,并且有着较高的收敛阶．

在科学实践、工程技术和日常生活中,人们常常会遇到大量的、各式各样的最优化问题.最优化方法在近几十年里获得了巨大的发展,但目前很多方法不同程度上还存在着一些不足之处.尤其是最终所求得的大多为局部最优解,并不是全局最优解.而近年来得到蓬勃发展的遗传算法其本质是一种求解问题的高效并行全局搜索方法.它能在搜索过程中自动获取和

本文就遗传算法的位串编码方案进行分析,充分利用遗传算法局部较强的优化操作方法, 提出基于Gray编码和锦标赛选择策略的采用全局搜索算子和局部搜索算子优化组合解决非线性优化问题的方案.经用C++编程对经典的Shubert与Banana测试函数进行实验测试.结果表明用该方案解非线性优化问题十分有效.

5由于受到并行计算的推动,十多年来,抛物型方程有限差分并行算法设计与分析一直得到关注.应

在矩形网格上建立了许多实际应用中很有效的二维抛物型方程的差分格式.在非矩形网格上近似解二维抛物型方程可以用有限元法.Winslow和曾经讨论过用差分方法在非矩形网格上求解二维抛物型方程的问题.本文用积分插值方法在非矩形网格上推导了一个二维抛物型方程的差分格式,并当网格为任意四边形时给出了一个经济格式和有关的数值结果.

本文介绍了产生随机数的几种重要方法,并且应用混合同余法对一个具有解析解的二维承压稳定地下水流数学模型进行了随机模拟计算,计算结果与解析解比较吻合,效果较好．

引言 许多物理应用问题求解的核心是如何高效求解稀疏线性方程组.直接解法由于在进行矩阵分解时常引入大量填充元,导致存储量与计算量一般很大,而且当系数矩阵条件数很大时,208数值计算与计算机应用2003年直接法稳定性差,使得任何中间舍入误差均可能引起最终计算结果

Using Bezier curves of degree n + 1 as design curves XA(t) on one plane and Bezier curves of degree n + m + 1 as adjoint curves XB(t) on another parallel plane, the conditions of constructing developable surfaces of degree (n+ 1, n + m+ 1) are discussed.These conditions are determined by the control vextexes of the two Bezier curves and the matching functions. Furthermore, the methods for constructing developable surface of degree (n + 1, n + 2) and compositive surfaces are derived.

本文提出一个以流体网格法为基础的计算多物质可压缩流体力学的数值方法,我们把它叫做多流体网格法。差分方程及算法过程与质点网格法相似,只是输运计算不采用质点网格法的质点,这就减少机器的存贮单元和计算时间。另一方面,也消除质点网格

The symmetric successive over relaxation- preconditioned conjugated gradient method (SSOR-PCG) is a very efficient iterative method for solving large sparse linear equations.In this paper an improved iterative format 0f the SSORPCG method is pressented,which avoids the product operation of coefficient matrix and direction vector and thus saves computation work about 8%-50%.

引言 核禁试后,在美国加速战略创新计划(ASCI)的推动下,世界和我国在高性能并行计算机研制、并行计算方法和并行软件研制上均取得长足发展,每秒上万亿次的高性能计算机对一般的科

In this paper, a non-overlapping domain decomposition method is discussed for solving the exterior boundary value problem of plane elasticity equation. The exterior domain is naturally decomposed by a circle into a bounded domain and an unbounded domain. With the advantage of the natural boundary reduction, a D-N method is presented. This method is effective and geometric convergent. The convergence rate of this iteration is independent of the finite element mesh size, but dependent on the relaxation factor.

A new sorting method, the method of code-transformation, graded computing and insertional relocations is presented. Its algorithm description, time complexity and experimental results in C are given. It's proved by algorithm analysis and ex- perimental results that its time complexity is O(N) and the new sorting algorithm is better than the quick sort etc. when data are in equidistribution.

§1.问题的提出 R~(n×m)表示所有n×m阶实对称阵集合,R~n=R~(n×1),R_r~(n×m)表示R~(n×m)中秩为r的子集,O~n是n阶正交阵之集,S~n表示n阶实对称阵的全体,A~+表示A的Moore-Penrose广义逆,I_k表示k阶单位阵,S_k=(e_k,e_(k-1),…,e_1)∈R~(k×k),其中e_i为单位阵I_k的第i列。R(A)表示A的列空间,N(A)表示A的零空间,rank(A)表示A的

112 数值计算与计算机应用2002年51.问题的提出矩阵反问题及逆特征值问题在工程中应用广泛,关于它们的

气固两相流动形式是最复杂的两相流动实例,其系统中的颗粒浓度较高,颗粒间的碰撞经常发生,从而导致细观层次上的颗粒运动具有复杂性,对于两相流动系统,拟流体模型以其大规模模拟的可行性在数值模拟领域中居重要地位。但是,拟流体模型的连续性假设

针对大型稀疏鞍点问题给出了一种含有待定参数的新迭代解法,将其称之为一般加速松弛方法,简记为GAOR方法．当参数α=时,新迭代方法是变成由Golub等人给出的SOR-Like方法．该迭代法的构成是基于对系数矩阵进行的一种分裂．迭代法需要选择一个预处理矩阵和待定参数,通过适当选取预处理矩阵和待定参数,新迭代法是收敛的,并且以定理的形式给出了新迭代方法的迭代矩阵的特征值和参数之间的基本等式,从而也导出了迭代法收敛的充分和必要条件．理论结果表明新方法更具有广泛性,并且适当的选择参数可以使新方法较SOR-Like方法具有更快的收敛速度．在文中的最后给出了迭代法的数值试验结果．

This paper, with the use of Fourier transform and the filtering theory of linear timeinvariant system, reaches a conclusion that there are high-pass filter characteristicsin derivative and low-pass filter characteristics in integration after analysising fromthe view point of filtering. On the basis above, the author explores the numericalalgorithm of calculus-FFT algorithms and its adaptable condition by combining thesampling theorem of time with frequency domain, which is popularized to the numericalcomputation (NC) of non-integral-order calculus. The analysis and results of NC showthat the algorithm is convenient, fast, and applicable for the NC of low-order calculus,and specially suited to the engineering computation. It will aid in the NC, practicalutilization and error analysis of non-integer-order calculus.

This paper presents a new method for trust region subproblems- Tangent Single Dogleg method, this method is proved by analysis and calculated results to be hotter than Powell's single dogleg method.

所谓Jacobi矩阵是指如下形式的矩阵:并且b_i>0(i=1,…,n-1)。 我们用J_(n-1)表示J_n的n-1阶顺序主子矩阵。 1967年,Hochstadt提出了如下Jacobi矩阵特征值反问题。 问题1。给定两组实数{λ}_(i=1)~n和{μ_i}_(i=1)~(n-1)且满足

§1.排序 对一组给定的数据记录 x_1,x_2,…,x_i,…,x_N (1)排序,就是在计算机上经过一定的计算处理,把数据记录(1)排成递增或递降的数序列。如排成递增的数序列

The simulation on a distributed parallel computer system requires parallel ran- dom number generators. In this paper, four algorithms of parallel random number generators are introduced. They are segmented parallel algorithm and leapfrog par- allel algorithm of multiplicative congruential generator and generalized feedback shift register (GFSR) generator, parallel algorithm of lagged-Fibonacci generator,and parallel algorithm of combined generator.

In this paper, we review some recent developments on the study of implicitly defined curves and surfaces in the field of computer aided geometric design(CAGD), includ-ing mainly the research on the problems of parametrization, regularity and splines of algebraic curves and surfaces.

This paper considers the following problem: How to construct a Jacobian matrix from its spectrum and a submatrix. A new numerical method is given.

（?） 随着计算机处理图形图象能力的增强,对计算几何理论与应用的研究,越来越为人们所重视.计算几何研究的是,如何高效处理通过视觉器官等途径得到的几何图形信息,开发高速解决几何问题的方法,从理论上探寻几何计算的复杂性与可行性,并对其性能做出评价.

Firstly, with the discusses of main ingredients to exert the peak float performance for currently high performance mirco-processors in detail, this paper analyzed the principal motivations for the speedup of parallel applied codes under the parallel computers consisted of the these micro-processors. Secondly, this paper presented a suite of performance evaluations rules for parallel codes, which can reveal the overall numerical and parallel performance with respect to the serial codes, pose the performance improving strategies, explain exactly the reasons for super-linear Speedup. The numerical experimential results of two realistic applied codes under two parallel computer are also given in this paper.

设F:D?R~n→R~n,用迭代法求非线性方程组 F(x)=0 (1)或 f_i(x_1,x_2,…,x_n)=0,i=1,…,n (1’)的解。初值x~0与解x必须充分靠近才能使迭代收敛,连续法提供了一个获得与解x充分靠近的初值。方法的出发点是引进参数t∈[0,1],并构造同伦算子H:[0,1]×D?[0,1]×R~n→R~n代替F,使当t=0时H(0,x)=0有一已知解x~0,当t=1时

由冯康提出的椭圆型微分方程的正则边界归化近年来已有不少发展。本文将扇形域及无穷扇形域上二类调和边值问题的正则积分方程离散化,得出了有限元解的误差估计公式。由于断裂及凹角扇形域上相应的Poisson积分公式准确反映了解在奇点的

Ray tracing is a basic aspect in tomography. To solve the caustic problem in inhomogeneous media using Maslov asymptotic theory, we need to calculate the position and slowness vector at every point. Therefore, ray tracing must rely on the ray equations in Hamiltonian form. In this paper, fourth order symplectic scheme and nonsymplectic Runge-Kutta scheme are compared in ray tracing for sinusoidal velocity model. The result indicates that ray paths obtained by two schemes are almost the same. But on keeping Hamilton quantities, the symplectic scheme is far better than the Runge-Kutta scheme. On computing travel time for Htamiltonian system with T parameter, we use trapezoid formula for numerical integration. The result coincides with that obtained using Hamiltonian system with t parameter.

Newton-GMRES方法是求解大规模稀疏非线性方程组的有效方法之一．由Newton- GMRES方法可以得到具有全局收敛性质的Newton-GMRES后退(NGB)方法．我们 就如何提高NGB方法的强健性问题进行了深入探讨,提出了两种改进NGB方法的全局策 略,并由此相应地得到了两种更为强健且具全局收敛性质的Newton-GMRES方法．