近似微分

Firstly, by adopting the thought of Adomian's decomposition method, the generic dynamic model in mechanical systems are transformed into a standard first-orderdifferential-equations, and then the inverse operator method for the approximate analytic solution of nonlinear mechanical system is developed based on the exact solution in form.

主要研 究工作如下：利用Adomian的分解方法的思想，把机械系统中最一般的动力学模型转化为一阶标准型微分方程组，以形式上的精确解的表达式为基础构造了求解机械系统非线性模型近似解析解的逆算符方法；针对机械系统非线性模型的特点，提出了直接处理高阶方程的不降阶逆算符方法；证明了该方法的收敛性。

The derivative of f with respect to x, which is the slope of the linear approximation to f.

f对x的微分，是对於函数f的线性近似。

On the basis of introducing the fixed point of Banach theorem, this paper firstly elaborates the important application of the existence of the solution of the linear algebraic equation and the ordinary differential equation, then it narrates the important application of obtaining the leading Newton repetitive process and the natural number the inferior square root and the equation root in the approximate calculation.

本文在介绍Banach不动点定理的基础上，首先阐述了其在线形代数方程、常微分方程解的存在性中的重要应用；然后讲述了其在求导Newton迭代法、求自然数的次平方根、求方程根的近似计算中的重要应用；最后，介绍了其在求一类递推数列极限中的应用。

The proposed scheme is developed using the local coordinate system based PML splitting equations and integral approaches of the PML equations under a discretization of triangular grid cells.

本方法的核心是建立局部坐标系下的分裂方程和基于积分近似的微分方程弱形式。

The theoretical analysis and simulation results show that, based on the differential geometry of the chaotic controller not only can eliminate the chaotic oscillation, but also be able to control the system to any given orbit, the effect was better than the traditional method of linear approximation.

分析和仿真结果显示，基于微分几何方法设计的控制器，不仅能够消除混沌振荡，而且能够把系统控制到任意给定轨道上，控制效果明显优于传统近似线性化方法。

Discrete calculus , discrete probability distribution s, discrete Fourier transform s, discrete geometry , discrete logarithm s, discrete differential geometry , discrete exterior calculus , discrete Morse theory , difference equation s, and discrete dynamical system s.

在应用数学中，离散模型连续模型的离散近似。在离散模型中，离散方程are fit to 数据。使用递推关系是这种建模方式的一般方法。时标微积分是差分方程理论与微分方程理论的统一，应用在需要建立离散和连续同步数据模型的领域。

This course provides a basic introduction of topics such as: interpolation, solution of nonlinear equations, curve fitting to measured data, numerical linear algebra, numerical integration, numerical differentiation, etc..

本课程介绍内容包括：内插法，非线性方程式求解，曲线近似法，线性代数数值运算，数值积分，数值微分等课题。

Secondly, point out that meshless method is different from finite element method in handling boundary condition and numerical integral because the approximation function of meshless method is not inserted function, it have itself special methods. Deduces meshless Galerkin essential equation of parabolic partial differential equation with the method ofweighted residuals------Galerkin. Furthermore, discusses the main factors which may effectthe calculation precision and give some suggestion with which can get the best result.

其次，由于无网格法的近似函数不是插值函数，所以无网格Galerkin法在处理边界条件和对区域积分时是不同于有限元的，它有其独特的处理方法，从加权残量法——Galerkin出发，推导出抛物型偏微分方程无网格Galerkin法的基本方程，并对影响无网格Galerkin法的主要因素进行探讨，给出了取得最佳效果的相应建议。

Therefore,it is necessary to research diffusion equation for suspended sediment because it describes the sediment move process in the water body.The equation is a various coefficients second-order linear partial differential equa-tion,such equation under complex boundary condition is very difficult to get its analytical solution,while its numerical solution relative analytical solution is more easier and has the obvious superiority:simple,the computation convenience.but to get a kind of difference format which is good accuracy and stability is not easy.

泥沙扩散方程实际上是一个变系数的二阶线性偏微分方程，这样的方程在各种复杂边界条件下求解是十分困难的，求它的解析解在数学上存在着难以克服的障碍，无法求出其精确解，因此常用数值方法求它的近似解，相比较而言，数值方法有着明显的优势：即简单灵活、计算方便快捷，但要寻找一种精度高、稳定性好、计算方便的差分格式也并非易事。

The paper introduces a differential equation derived from Markov theory and probability generating function.

文章介绍用Markov理论与母函数方法建立相关微分方程，并导出近似解析解，着重对常数源在系统中的涨落作了数学描述，给出了数值例子。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。