## 数学代写|有限元方法代写Finite Element Method代考|EG55M1

2022年9月27日

couryes-lab™ 为您的留学生涯保驾护航 在代写有限元方法Finite Element Method方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写有限元方法Finite Element Method代写方面经验极为丰富，各种代写有限元方法Finite Element Method相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础
couryes™为您提供可以保分的包课服务

## 数学代写|有限元方法代写Finite Element Method代考|Functional derivative

While the dependent variable changes from $u$ to $u+\delta u$ the functional changes from $I(u)$ to $I(u)+\delta I(u)$. The variation represents a change from a stationary function to a function close to it. Therefore, in order to find the stationary function the variation of the functional would have to be zero. Let’s consider the variation of a functional that is a function of $u$ and $u_{, x}$, such as Eq. (3.21). Let’s also assume that this functional does not vary on its boundaries. The stationary value of such a function, can be found by setting the variation of the functional to zero,
$$\delta I(u)=\delta \int_{x_0}^{x_L} F\left(x, u, u_{, x}\right) d x=\int_{x_0}^{x_L} \delta F\left(x, u, u_{, x}\right) d x=0$$
The variation of the function $F$ inside the functional can be expressed as follows $[2]$
$$\delta F=\frac{\partial F}{\partial x} \delta x+\frac{\partial F}{\partial u} \delta u+\frac{\partial F}{\partial u_{, x}} \delta u_{, x}$$
However, the variational operator $\delta$ measures the change of the value of the functional as the function $u$ is varied. In fact it is not concerned with the effects of point-to-point changes in $u$. Thus the first term in Eq. (3.32) is zero, and the variational derivative of $F\left(x, u, u_{, x}\right)$ becomes,
$$\delta F=\frac{\partial F}{\partial u} \delta u+\frac{\partial F}{\partial u_{, x}} \delta u_{, x}$$
It is instructive to note the similarities and the differences between the variational derivative operator and the total differential operator. Recall the total differential $d f$ of a function $f=f(x, y, z)$ is given as follows:
$$d f=\frac{\partial f}{\partial x} d x+\frac{\partial f}{\partial y} d y+\frac{\partial f}{\partial z} d z$$
and, the total differential $d F$ of the function $F\left(x, u, u_{, x}\right)$ is given as follows:
$$d F=\frac{\partial F}{\partial x} d x+\frac{\partial F}{\partial u} d u+\frac{\partial F}{\partial u_x} d u_{, x}$$
As stated above the variation sought by the variational operator is on the effects of the value of the function but not on the effects of the point-to-point variations of the function. This is sometimes stated as the variational operator $\delta$ seeks a variation of $F$ at a fixed $x$ location.

## 数学代写|有限元方法代写Finite Element Method代考|Properties of functionals

A generic functional $I(u)$ is linear if it satisfies the following condition:
$$I(\alpha u+\beta v)=\alpha I(u)+\beta I(v)$$
where $\alpha$ and $\beta$ two arbitrary scalars and $u$ and $v$ are two arbitrary functions. A generic functional $B(u, v)$ of two dependent variables is bilinear if both dependent variables can be shown to be linear separately. The linearity of the first argument can be shown if the following statement can be satisfied,
$$B\left(\alpha u_1+\beta u_2, v\right)=\alpha B\left(u_1, v\right)+\beta B\left(u_2, v\right)$$

where $u_1$ and $u_2$ are two arbitrary functions. Similarly the linearity of the second argument can be shown if,
$$B\left(u, \alpha v_1+\beta v_2\right)=\alpha B\left(u, v_1\right)+\beta B\left(u, v_2\right)$$
can be satisfied for any dependent variables $v_1$ and $v_2$. A bilinear functional is symmetric if the following statement can be demonstrated:
$$B(u, v)=B(v, u)$$

# 有限元方法代考

## 数学代写|有限元方法代写有限元法代考|函数导数

$$\delta I(u)=\delta \int_{x_0}^{x_L} F\left(x, u, u_{, x}\right) d x=\int_{x_0}^{x_L} \delta F\left(x, u, u_{, x}\right) d x=0$$

$$\delta F=\frac{\partial F}{\partial x} \delta x+\frac{\partial F}{\partial u} \delta u+\frac{\partial F}{\partial u_{, x}} \delta u_{, x}$$

$$\delta F=\frac{\partial F}{\partial u} \delta u+\frac{\partial F}{\partial u_{, x}} \delta u_{, x}$$
。注意变分导数算子与全微分算子之间的异同是有指导意义的。函数$f=f(x, y, z)$的总微分$d f$如下:
$$d f=\frac{\partial f}{\partial x} d x+\frac{\partial f}{\partial y} d y+\frac{\partial f}{\partial z} d z$$
，函数$F\left(x, u, u_{, x}\right)$的总微分$d F$如下:
$$d F=\frac{\partial F}{\partial x} d x+\frac{\partial F}{\partial u} d u+\frac{\partial F}{\partial u_x} d u_{, x}$$

## 数学代写|有限元方法代写有限元法代考|泛函的性质

$$I(\alpha u+\beta v)=\alpha I(u)+\beta I(v)$$

$$B\left(\alpha u_1+\beta u_2, v\right)=\alpha B\left(u_1, v\right)+\beta B\left(u_2, v\right)$$

，则可以证明第一个参数的线性

$$B\left(u, \alpha v_1+\beta v_2\right)=\alpha B\left(u, v_1\right)+\beta B\left(u, v_2\right)$$

$$B(u, v)=B(v, u)$$

## 有限元方法代写

tatistics-lab作为专业的留学生服务机构，多年来已为美国、英国、加拿大、澳洲等留学热门地的学生提供专业的学术服务，包括但不限于Essay代写，Assignment代写，Dissertation代写，Report代写，小组作业代写，Proposal代写，Paper代写，Presentation代写，计算机作业代写，论文修改和润色，网课代做，exam代考等等。写作范围涵盖高中，本科，研究生等海外留学全阶段，辐射金融，经济学，会计学，审计学，管理学等全球99%专业科目。写作团队既有专业英语母语作者，也有海外名校硕博留学生，每位写作老师都拥有过硬的语言能力，专业的学科背景和学术写作经验。我们承诺100%原创，100%专业，100%准时，100%满意。

## MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。