差分系数

Using this method, we obtain the difference equation with variable coefficients and a fixed order.

使用这种离散方法，我们得到变系数但不变阶的差分方程。

Because the equation is a various coefficients second-order parabolical partial differential equation,explicit difference formats usually have high condition for stability. Implicit difference formats have good stability,but they must calculate a set of algebraic equations,which are too complex.

由于泥沙扩散方程是一个二维变系数的抛物型方程，对于多维的方程，显格式往往稳定性要求很高，而隐格式虽然稳定性较好，但它要解大型的代数方程组，工作量也非常大，为了克服这两种格式的不足，常用ADI法求解，但仍存在一些计算量偏大等不足之处，因此构造出更好的差分格式是有必要的。

The authors studied carefully two numerical differential methods, finite difference method and rational polynomial technique, and pointed that FDM is the special ease of RPT when the limit state function is linear. Accordingly, FDM3 can be used for the continuous linear limit state function and RPT5 for the continuous nonlinear limit state function. For the discontinuous limit state function, RPT should be used because of the large error of FDM.

对于可靠度分析中常用的有限差分法及有理多项式法这两种数值微分方法，本文详细研究了二者间的异同及其求导结果与步长的关系，指出了对于相同的步长控制系数及取样方式，FDM是RPT在线性情况下的特例；对于连续的线性功能函数，可直接用3点FDM求导；对于连续的非线性功能函数，可用5点RPT求导；对于非连续的功能函数，应采用RPT求导。

The truncation error of CSCD is derived and compared with some symmetric finite difference methods having the same order of accuracy,which shows that CSCD has the smallest coefficients in error terms.

从定性角度，得出同阶中心差分格式中，CSCD格式的截断误差系数最小的结论。

In this paper, the oscillation of forced neutral difference equations with positive and negative coefficients is studied and two sufficient conditions of this equation to be oscillatory are obtained.

研究了一类具有强迫项正负系数中立型差分方程的振动性，获得了方程振动的两个充分条件。

The topics covered in these sections are the geometric interpretation of systems of linear equations, the classification of finite symmetry groups in two and three dimensions, the exponential of a matrix and its application to solving systems of first order linear differential equations with constant coefficients, and Hurwitz's theorem on the composition of quadratic forms.

这些条文所涉及的主题是线性方程组的几何解释，在两个和三个有限对称群的分类方面，一个矩阵及其应用，以解决一阶常系数线性差分方程，系统指数赫尔维茨定理在二次形式组成。

Analyzing the effection of calculated results under different calculated conditions,such as different time step,relaxation coefficient,numerical methods and wall difference methods.

分析了不同的时间步长、加速系数、数值方法和壁面差分方法对计算结果的影响。

According to fully implicit method, seepage model of low-permeability fractured gas reservoirs are discretized with finite difference method, and corresponding numerical model, coefficient matrix and matrix element are obtained; then based on modern software engineering, numerical simulation software was correspondingly developed with Fortran95 programming language

按照全隐式离散化方法，采用有限差分方法对低渗裂缝性气藏渗流数学模型进行了离散，得到了相应的数值模型、系数矩阵和矩阵元素。然后基于现代软件工程的基本思想，用Fortran95语言开发了相应的数值模拟软件

The patial differential equations with singular coefficients are very important ones in the field of numerical mathematics.

具有奇异系数的椭圆及抛物偏微分方程是一类很重要的方程，最近十几年，计算数学工作者利用有限差分、有限元等方法对此类问题进行了深入的研究并得到了很好的结果。

In chapter 3,we extend the differece format in chapter 2 to two-dimensional changing coefficient parabolic equation.

在第三章，我们将第二章的差分格式推广到二维变系数抛物型方程中去。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。