Viscoelastic

说明：  在科学与工程计算中，经常遇到求解非线性方程组的问题；非线性方程组在收敛速度及收敛性比线性方程组要差，特别对于非凸的非线性方程组，其求解更是困难。下面简要介绍非线性方程组的三种解法——牛顿法、拟牛顿法、同伦算法，分析三种解法的适用性，并附Matlab原程序。(Scientific and engineering computing, often encounter the problem of solving nonlinear equations speed of convergence of nonlinear equations and linear equations worse than convergence, especially for non-convex nonlinear equations, which is even more difficult to solve . The following briefly describes three solutions to nonlinear equations- Newton method, quasi-Newton method, homotopy method, the applicability of the three solutions, along with Matlab original program.)

Dsimplex.m 对偶单纯形法求解线性规划问题(Dual simplex method for solving linear programming problems)

说明：  共轭梯度法（Conjugate Gradient）是介于最速下降法与牛顿法之间的一个方法，它仅需利用一阶导数信息，但克服了最速下降法收敛慢的缺点，又避免了牛顿法需要存储和计算Hesse矩阵并求逆的缺点，共轭梯度法不仅是解决大型线性方程组最有用的方法之一，也是解大型非线性最优化最有效的算法之一。 在各种优化算法中，共轭梯度法是非常重要的一种。其优点是所需存储量小，具有步收敛性，稳定性高，而且不需要任何外来参数。(Conjugate gradient method Gradient) is a method between the steepest descent method and Newton's method. It only uses the first derivative information, but overcomes the disadvantage of slow convergence of steepest descent method, and avoids the disadvantage of storing and calculating Hesse matrix and solving inverse of Newton's method. Conjugate gradient method is not only one of the most useful methods to solve large-scale linear equations, but also the most effective method to solve large-scale nonlinear optimization One of the algorithms of. Among all kinds of optimization algorithms, conjugate gradient method is very important. It has the advantages of small storage, step convergence, high stability and no external parameters.)

calculate maximum volume of cuboid given conditions.. a+b+c<s ab+bc+ca<d where s and d are constants..

sap4源代码！by fortran 这是一个有限元计算的软件 可以完成平面，三维的计算功能(SAP4 source code! By FORTRAN This is a finite element software can be completed planar, 3D computing power)

一些简单的UDF文件，实现流场中梯度和某一点压力的检测提取(Some UDF profiles)

多目标粒子群的matlab程序，文中设置了两个目标，f1和f2，采用加权求解的方式(more goals in Matlab PSO procedures, the text set up two goals, f1 and f2. using the weighted solution!)

提供函数能进行1维2维的FFT，输入输出的序列长度应为2的整数次方倍(Provides functions can be one-dimensional two-dimensional FFT, sequence length input and output should be an integer power of 2 times)

FFT（Fast Fourier Transformation）是离散傅氏变换（DFT）的快速算法 [1] 。即为快速傅氏变换。它是根据离散傅氏变换的奇、偶、虚、实等特性，对离散傅立叶变换的算法进行改进获得的。(FFT (Fast Fourier Transform) is a fast algorithm of discrete Fourier Transform (DFT). That is fast Fourier transform. According to the odd, even, imaginary and real characteristics of discrete Fourier transform, the algorithm of discrete Fourier transform is improved.)

说明：  Galerkin method,a numerical approximate method based on weighted residual method,commonly used in differential equation.(Galerkin method,a numerical approximate method based on weighted residual method,commonly used in differential equation.)