homework3

自己写了一个二维Euler方程的间断有限元程序 上次发了一个三角形单元的程序 因为不是曲边单元 所以在圆柱后面容易形成涡 现在把程序改为曲边四边形单元了 没有涡出现 单元是8节点四边形单元 节点编号顺序是 1 5 2 6 3 7 4 8 也就是四个角点依次 是1 2 3 4 然后是边的中点编号 5 6 7 8. 时间推进采用 Runge-Kutta 方法 数值通量采用全局Lax-Friedrichs通量 仍然不能捕捉激波 因为没有做重构或者加人工粘性 等这个做出来了 再发一次。 程序没有进行优化 比如说内存的消耗没有优化 比如直边单元的边界积分仍然采 用了曲边的积分方法 增加了计算量 比如面积分、线积分都是采用的是Gauss- Legendre-Lobatto积分 积分精度会比一般的Gauss-Legendre积分精度低一阶 等 等问题。 二维的 纯属交流性质 就没有考虑这些问题 ^_^ 如果物面全部是直边 那么只要改变一个参数N 就可以获得不同的计算精度 且具 有谱精度 因为单元的节点是Gauss-Legendre-Lobatto积分点。 其实就是谱元法 （物面是曲边的情况我不清楚是不是也可以通过提高基函数的阶数 也就是增加N 来提高计算精度）(Wrote a two-dimensional Euler equations with discontinuous finite element program Last made ​ ​ a triangular element of the program, not curved edge unit is so easy to form a vortex in the cylinder behind the Program to curved edge quadrilateral element vortices appear Unit is the order of 8-node quadrilateral element node number is 15,263,748 which is the four corners of the points in turn Is 1234 and then the side of the midpoint of the number 5678. Time promote the use of Runge-Kutta method Numerical flux of the overall situation of Lax-Friedrichs, flux Still can not capture the shock wave did not do the reconstruction or artificial viscosity do it Zaifayici. The program is not optimized for example, memory consumption is not optimized such as straight-edge boundary integral of the unit is still mining Integral method to increase the amount of computation such as surface integral with a curved edge, the line integral using the Gauss- The Legendr)

fortran based code for 1d heat equation

一阶偏微分方程的基础知识，很容易入门,很多工程处理要用到的(Introduce the basic knoeledge of Partial Differential Equation)

abaqus drucker-prager UMAT字程序(abaqus drucker-prager UMAT subroutine)

二维情况的chan定位算法，1994年原版论文代码实现，可以支持远近和linear nonlinear四种模式(2 dimension chan algorithm, TDOA localization. Including near, far field and linear nonlinear sensor array)

说明：  对该模型参数辨识采用递推最小二乘法，即 RLS（ recurisive least square）， 它是一种能够对模型参数进行在线实时估计的辨识方法。(The recursive least square method is used to identify the parameters of the model, that is, rls (recurisive least square), which is an online real-time estimation method for the model parameters)

最小二乘法回报潮汐水位，根据dooson数回报潮汐，并计算调和常数，余水位，高潮和低潮的数值。(Least squares method returns tide level, tidal according dooson return number, and calculate the harmonic constants, values ​ ​ more than the water level, high tide and low tide.)

一种继续概率学习矩阵的优化算法，优化精度和计算时间都很不错，是目前基本最好的启发式算法，里面有测试函数(A continuing study probability matrix optimization algorithm to optimize the accuracy and computational time is very good, the best is the basic heuristic algorithm, which has test function)

几个使用的解线性方程组的程序，包括高斯消去法，高斯列主元法，高斯——赛德尔消去法。简明实用。(Gauss elimaination, Gauss_seidel ellimination)

用于数值积分的稀疏网格高斯埃尔米特方法,可以产生积分节点和积分系数(Sparse Grids Based on Gauss-Hermite Rules)