数理统计学小史

（三）狄莫弗的二项概率逼近为了使频率Ｘ／Ｎ与概率ｐ接近到ε而其可靠度不小于给定的ｃ／（ｃ＋１），试验次数Ｎ至少须达到多少？在前一讲中我们介绍了伯努利提供的一个答案，与此同时，伯努利的侄子，《推测术》的定稿人尼科拉斯·伯努利也提供了一个答案：记ｐｄ＝ｐ...     

小朋友学习珠心算

八、多位减法（一）借位与不借位 两同位数相减，某一位“被减数〉减数”为不借；“被减数=减数”有可能借，也有可能不借，为危险；“被减数〈减数”要向前借数，为借，     

对一道求数列通项问题的多角度切入

题目 已知数列{an）的前n项和为Sn，a1=2，当n≥2时，Sn=2n-nan． （1）求a2，a3； （2）求数列{an}的通项公式．     

数项级数项的重组及其对级数敛散性的影响

对级数为任意实数）的项进行某种重新组合，会影响级数的敛散性吗，本文将就这个有趣的问题进行讨论。一、若不改变级数项的排序，只对级数的项加括弧来重新组合，则1．原来收敛的级数加括弧后仍是收敛的，且和不变。这是收敛级数的一个基本性质（参见一般高等数学教材），利用这个结论，可以判断一些级数的敛散性。例1已知，讨论级数上的敛散性。解对级数已的项加括弧，由结论1知，级数上收敛，且其和为——一c”2，zZ，Z＋1”’———”——””‘””“““““－2．对敛散性未知的级数若加括弧后收敛．原级数仍可能发散。例如级数门一1…     

要善于发挥“虚借减法”在扭亏增盈中的积极作用

在亏损企业的核算工作中，虚借减法是少不了的内容和方法。要使企业转亏为盈，就需要重视并要善于发挥“虚借减法”在扭亏增盈中的积极作用。     

一类模糊神经网络

本文介绍了一个Ｆｕｚｚｙ神经网的三种基本形式，情况（１）是输入是实数，但权重和（或）偏差项是模糊的；情况（２）是输入是模糊的，但权重和偏差项是实数，情况（３）是输入模糊的，同时权重和（或）偏差项也是模糊的，本文集中研究情况（１），并主要讨论了情况（１）的模型性能（能力）而且得到一个较好的结果。     

两个正数的各种中项及其求法

以两个正数的等差中项、等比中项及调和中项为基础，通过极限方法引进等差-等比中项、调和-等比中项及等差-调和中项的概念，并导出它们的求法．     

二项展开式系数的求法

对于(a b)^n展开式中特定项的系数，常常从通项公式人手，学生容易掌握，而对于较复杂的展开式，如(a b)^m(c d)^n、(a b c)^n等，多有畏难情绪，这里介绍三种行之有效的方法，供大家学习时参考。     

高阶差等比数列

问题1 老鼠繁殖中的数学：正月里，老鼠的爸爸和妈妈生了12只小老鼠(6雌6雄)，这样，小老鼠和它们的爸爸妈妈加在一起就是14只，这些小老鼠到二月里当爸爸妈妈了，它们每一对又各生了12只老鼠，小老鼠一共6对，和它们的爸爸妈妈合起来，一共生了84只，(雌雄各半)，这样祖孙三代共有98只老鼠．     

回归分析在测定最佳图书复本量中的应用

本文从调查图书馆图书复本量分布及其读者借阅图书的分布情况出发，应用回归分析方法得出图书复本量与实际拒借率为双曲线回归关系，并以求解该双曲线的最大曲率点坐标，测得最佳图书复本量的值和对应的理想拒借率。     

On the Convergence of the Cross-Entropy Method

The cross-entropy method is a relatively new method for combinatorial optimization. The idea of this method came from the simulation field and then was successfully applied to different combinatorial optimization problems. The method consists of an iterative stochastic procedure that makes use of the importance sampling technique. In this paper we prove the asymptotical convergence of some modifications of the cross-entropy method.     

复合材料旋转壳非线性稳定性分析计算

利用前屈曲一致理论和能量变分法分析计算了复合材料旋转壳非线性稳定性.前屈曲应变-位移关系采用非线性的卡门方程,能量积分采用数值积分,用势能最小原理求解前屈曲位移和内力,提出了求解临界载荷的实用计算方法,用FORTRAN语言编制了相应的计算机程序,并给出了算例.     

On the accuracy of the projection computation of the collision integral

The accuracy of the projection method as applied to the computation of the collision integral is analyzed. It is shown that the method has an error of the second order of smallness with respect to the mesh size. An optimal method for choosing additional nodes that minimizes the computational error is found. The theoretical conclusions and the optimality of the method are confirmed in a series of numerical experiments.     

The estimation of the strength of the heat source in the heat conduction problems

A general method is proposed to determine the strength of the heat source in the Fourier and non-Fourier heat conduction problems. A finite difference method, the concept of the future time and a modified Newton–Raphson method are adopted in the problem. The undetermined heat source at each time step is formulated as an unknown variable in a set of equations from the measured temperature and the calculated temperature. Then, an iterative process is used to solve the set of equations. No selected function is needed to represent the undetermined function in advance. Three examples are used to demonstrate the characteristics of the proposed method. The validity of the proposed method is confirmed by the numerical results. The results show that the proposed method is an accurate and stable method to determine the strength of the heat source in the inverse hyperbolic heat conduction problems. Furthermore, the result shows that more future times are needed in the hyperbolic equation than that of parabolic equation. Moreover, the robustness and the accuracy of the estimated results in the non-Fourier problem are not as well as those of the Fourier problem.     

Accelerating the convergence in the single-source and multi-source Weber problems

The modified Weiszfeld method [Y. Vardi, C.H. Zhang, A modified Weiszfeld algorithm for the Fermat-Weber location problem, Mathematical Programming 90 (2001) 559-566] is perhaps the most widely-used algorithm for the single-source Weber problem (SWP). In this paper, in order to accelerate the efficiency for solving SWP, a new numerical method, called Weiszfeld-Newton method, is developed by combining the modified Weiszfeld method with the well-known Newton method. Global convergence of the new Weiszfeld-Newton method is proved under mild assumptions. For the multi-source Weber problem (MWP), a new location-allocation heuristic, Cooper-Weiszfeld-Newton method, is presented in the spirit of Cooper algorithm [L. Cooper, Heuristic methods for location-allocation problems, SIAM Review 6 (1964) 37-53], using the new Weiszfeld-Newton method in the location phase to locate facilities and adopting the nearest center reclassification algorithm (NCRA) in the allocation phase to allocate the customers. Preliminary numerical results are reported to verify the evident effectiveness of Weiszfeld-Newton method for SWP and Cooper-Weiszfeld-Newton method for MWP.     

On the regularizing properties of the GMRES method

Summary. The GMRES method is a popular iterative method for the solution of large linear systems of equations with a nonsymmetric nonsingular matrix. However, little is known about the behavior of this method when it is applied to the solution of nonsymmetric linear ill-posed problems with a right-hand side that is contaminated by errors. We show that when the associated error-free right-hand side lies in a finite-dimensional Krylov subspace, the GMRES method is a regularization method. The iterations are terminated by a stopping rule based on the discrepancy principle. Received November 10, 2000 / Revised version received April 11, 2001 / Published online October 17, 2001     

Implicit difference approximation for the time fractional heat equation with the nonlocal condition

In this work, a method for solving inhomogeneous nonlocal fractional heat equations is proposed. The method is based on the modified Gauss elimination method. It is proved by using matrix stability approach that the method is unconditionally stable. Numerical results are provided to illustrate the accuracy and efficiency of the proposed method.     

从模糊现象中识别物理机制的证据论方法

本文提出了一种新的模糊模式识别方法。这种方法第一步是从已有的物理现象中，提取出支持不同类物理机制的“证据”，证据的提取采用了文中提出的模糊数学方法。第二步是去比较支持不同物理机制的证据，最后一步是给出模糊模式识别结果。本文把证据论和数学成功地结合起来，建立新的模糊识别方法。虽然，新方法可望在广泛的领域中得到应用，最后，本文用所提方法研究了炉霍地震（１９７３，Ｍｓ＝７．９）的破裂机制。     

An extension of the Krylov method for calculating the coefficients of the minimal polynomial

The concept of a k-minimal polynomial of an operator is introduced, and a method for approximate calculation of the coefficients of this polynomial is proposed. The method uses the calculated values of certain functionals on iterations of the operator. Special features emerging when the algorithm is used in combination with the Monte Carlo method are discussed, and numerical results are given.     

从常步长梯度方法的视角看不可微凸优化增广Lagrange方法的收敛性

增广Lagrange方法是求解非线性规划的一种有效方法.从一新的角度证明不等式约束非线性非光滑凸优化问题的增广Lagrange方法的收敛性.用常步长梯度法的收敛性定理证明基于增广Lagrange函数的对偶问题的常步长梯度方法的收敛性,由此得到增广Lagrange方法乘子迭代的全局收敛性.