谈不定积分运算中的一些灵活性

众所周知 ,在求一些函数的导数时 ,无论给定函数表达式有多么复杂 ,我们总可以按照求导法则 ,按部就班地求出其导函数。也许正是因为求导过程比较简捷明了 ,从而决定了它的逆过程即求不定积分的过程似乎变得复杂而烦琐 ,没有一个统一的法则可以遵循。但恰恰由于这种复杂性 ,也预示着求它的方法是灵活多变的 ,技巧性也是较强的。下面仅就不定积分运算中的一些灵活技巧给予诠释。例 1　求 :∫x +sinx1 +cosxdx解　原式 =∫( x1 +cosx+sinx1 +cosx) dx =　 (注 :( tanx2 )′=11 +cosx,sinx1 +cosx=tanx2 )∫xdtan x2 +∫tanx2 dx =xtanx2 +C本…     

关于矩阵函数微分学的一个注记

介绍了以矩阵为变元的函数的微分及其运算法则.与通常的求导运算相比,这里介绍的微分运算理论上更加自然、简洁,使用起来更加容易、更加方便.事实上,矩阵导数应当视为由微分运算派生出来的运算.     

关于用初等变换求A^—1

线性代数中,矩阵的初等变换是非常重要的运算手段。在求矩阵的秩、逆矩阵、向量的线性相关性及求解线性方程组等方向却用到了行(列)的初等变换。一般的教材在介绍逆矩阵的初等变换求法时都强凋了仅用行初等变换。实     

关于三角形Toeplitz系统的复杂性

目前,已有结果表明,作两个n阶上(或下)三角形T矩阵的乘积以及做n阶三角形T矩阵乘n维列向量的算术运算次数,均不超过O(nlog_2n);而求n阶三角形T矩阵的逆,其工作量则不超过O(nlog_2~2n). 本文给出三角形T矩阵求逆与求解三角形Toeplitz线性方程组的快速算法.该算     

应用初等变换解决向量的线性表出问题

应用初等变换解决向量的线性表出问题雷英果（福州大学）由于向量的加、减、数乘运算是线性代数的基本运算。初等变换在线性代数中起着重要的作用。我们可以用初等变换计算行列式，求矩阵的逆，计算矩阵的秩，解线性方程组，化矩阵为对角形，．．．等等。但是，在求解把向...     

实变复值函数在微积分中的应用

实变复值函数的运算遵从普通实函数的运算定律,利用实变复值函数可以简捷方便地求解高阶导数和不定积分.     

行列式映射唯一性的一个证明

仅在已知矩阵的乘法运算以及矩阵的逆的定义的条件下,证明数域F上全体可逆矩阵GL(F)到非零数集F*的行列式映射是唯一存在的     

析谈单元函数积分的基本概念与基本理论

<正> 单元函数积分学包含不定积分和定积分这两部分内容,其中原函数、不定积分和定积分的概念是其基本概念,积分中值定理、上限是变量的定积分及其求导定理是其基本理论,而Newton-Lebniz公式是其基本公式,积分法是其基本的运算法.本文将侧重围绕着积分学的基本概念和基本理论,论述三个关系,即原函数与不定积分;不定积分与定积分;原函数的存在性与可积性的关系以及积分中值定理.     

伪逆矩阵及其在改进型BP神经网络中的应用

基于伪逆矩阵理论,将sigmoid型激励函数与隶属函数相结合,构造出了改进型三层BP神经网络模型。该网络模型可以确定隐含层神经元个数,并给出了权值直接确定算法下的最优权值矩阵,最优权值矩阵就是计算输入受激励矩阵的伪逆矩阵与输出向量的乘积,突出了改进型BP神经网络就是基于训练数据的矩阵方程求解的特殊表示。仿真实验验证了该网络具有极高的逼近精度,且运行时间较短。     

导数公式推导的启发式教学方法

针对一般微积分教材中函数的积、商求导法则、反三角函数的求导公式和参数式函数的二阶求导公式,提供几种简明易懂的启发式教学方法,对导数的运算有很好的参考价值.     

An Iterative Algorithm for the Coefficient Inverse Problem of Differential Equations

In this paper, an iterative algorithm for solving a coefficient inverse problem is submitted. The key of the method is to project an unknown coefficient function on a finite dimensional function space. Thus, the inverse problem can be changed into a nonlinear algebraic system of equations.     

On Regularization of a Source Identification Problem in a Parabolic PDE and its Finite Dimensional Analysis

We consider the inverse problem of identifying a general source term, which is a function of both time variable and the spatial variable, in a parabolic PDE from the knowledge of boundary measurements of the solution on some portion of the lateral boundary. We transform this inverse problem into a problem of solving a compact linear operator equation. For the regularization of the operator equation with noisy data, we employ the standard Tikhonov regularization, and its finite dimensional realization is done using a discretization procedure involving the space $L^2(0,\tau;L^2(Ω))$. For illustrating the specification of an a priori source condition, we have explicitly obtained the range space of the adjoint of the operator involved in the operator equation.     

A Parametrization of the Irreducible Representations of a Compact Inverse Semigroup

The aim in this article is to provide a parametrization of the finite dimensional irreducible representations of a compact inverse semigroup in terms of the irreducible representations of maximal subgroups and order theoretic properties of the idempotent set. As a consequence, we obtain a new, and more conceptual, proof of the following theorem of Shneperman: a compact inverse semigroup has enough finite dimensional irreducible representations to separate points if and only if its idempotent set is totally disconnected. Moreover, we also prove that every norm continuous irreducible *-representation of a compact inverse semigroup on a Hilbert space is finite dimensional.     

Hilbert空间中算子广义逆的积分表示

利用算子矩阵分块的技巧,得到了Hilbert空间中算子的Moore-Penrose逆和Drazin逆的积分表示.给出了较为简洁的证明,同时将有限维的结论推广到无限维的情形.     

一类双曲反问题的逼近算法及收敛性

该文考虑地球物理勘探中出现的间断特性阻抗的反演问题．利用样条插值理论，把无穷维空间上的反问题用有限维空间上的反问题来近似．利用半群理论，证明了近似反问题之解收敛于原反问题之解．据此可得到求解反问题的一种稳定的近似算法．     

On power-bounded operators and operators satisfying a resolvent condition

We obtain, by means of a classification of the eigenvalues, local estimates for holomorphic. functions of a class of linear operators on a finite dimensional linear vector space. We apply these methods to find new proofs of some theorems ofKreiss andMorton, and in addition we give a local estimate of the powers of the inverse of any nonsingular operator in this class.     

Linear operators in finite dimensional probabilistic normed spaces

In this paper, we consider strongly bounded linear operators on a finite dimensional probabilistic normed space and define the topological isomorphism between probabilistic normed spaces. Then we prove that every finite dimensional probabilistic normed space which is a topological vector space is complete.     

A method of continuous time approximation of delayed dynamical systems

This paper presents a new method to analyze response of linear and nonlinear dynamical systems with time delay. The method proposes a continuous time approximation of the delayed portion of the response. This leads to a high and finite dimensional state space formulation of the time-delayed system. The advantage of the current method lies in that the resulting finite dimensional state equations are in the standard state space form, making all the existing analysis methods and control design tools for linear and nonlinear dynamical systems amenable to the current approach. The method can also handle multiple independent time delays in a natural way. One- and two-dimensional dynamical systems with time delay are used to demonstrate the effectiveness of the method.     

Ovoids in finite uniform linear spaces

The concept of an ovoid is extended to linear spaces, and it is shown that a finite uniform linear space with an ovoid is either a trivial structure on a finite set, or else either two or three dimensional. In the three dimensional case, the ovoid is directly related to an inversive plane, in much the same way that an ovoid in a finite projective space is.Dedicated to Professor Tallini on the occasion of his 60th birthday     

On the superlinear convergence of the variable metric proximal point algorithm using Broyden and BFGS matrix secant updating

In previous work, the authors provided a foundation for the theory of variable metric proximal point algorithms in Hilbert space. In that work conditions are developed for global, linear, and super–linear convergence. This paper focuses attention on two matrix secant updating strategies for the finite dimensional case. These are the Broyden and BFGS updates. The BFGS update is considered for application in the symmetric case, e.g., convex programming applications, while the Broyden update can be applied to general monotone operators. Subject to the linear convergence of the iterates and a quadratic growth condition on the inverse of the operator at the solution, super–linear convergence of the iterates is established for both updates. These results are applied to show that the Chen–Fukushima variable metric proximal point algorithm is super–linearly convergent when implemented with the BFGS update. Received: September 12, 1996 / Accepted: January 7, 2000?Published online March 15, 2000