FVM-Euler-2D

说明：  LDL分解。作为矩阵方程数值解法最基础的矩阵分解算法，LDL算法可以高效分解对称矩阵。(LDL decomposition. Numerical Solution of matrix equation as the most basic matrix factorization algorithm, LDL decomposition algorithm can be efficient symmetric matrix.)

说明：  主要用于Fluent 中风剖面、湍流剖面以及耗散率剖面的开发，应用的是日本的规范。(It is mainly used for the development of fluent stroke profile, turbulence profile and dissipation rate profile, and it is applied to the specifications of Japan.)

说明：  关闭OFDM信号子载波，画出OFDM信号频谱图，查看旁瓣泄露情况(Close OFDM signal sub-carrier OFDM signal spectrum plot, view the situation sidelobe leakage)

采用相互垂直的两个振子构成圆极化天线的FDTD程序．可以计算其圆极化波瓣宽度等天线指标 (perpendicular to each other using the two oscillator constitute a circularly polarized antenna FDTD procedures. Can calculate its lobed circular polarization antennas width indicators)

欧拉角和四元数的转换：输入偶欧拉角，按Rechnen，程序会自动将欧拉角转换为四元数，再得出最终的方位。(Euler angles and quaternion conversion: input dual Euler angles, press Rechnen, the program will automatically Euler angles conversion quaternion, and then come to the final orientation.)

数值计算实例，主要有LU分解，龙格库塔法，高斯分解法，欧拉法，曲线拟合，曲线插值(Numerical example)

33节点基于前推回代法的含分布式电源配电网的潮流计算程序，其中含支路阻抗的原始数据。(33 nodes with distributed power distribution network procedures, the former push back method, with branch impedance of the original data.)

计算等径双圆筒透镜的场分布，并画出等位线分布图(Calculation of Electron Physics )

复合材料破坏失效vumat子程序，使用hsshin准则判断失效，具有刚度缩减，(The VUMAT subroutine for failure of composite materials is judged by hsshin criterion, and stiffness is reduced.)

说明：  Description 设a[0…n-1]是一个包含n个数的数组，若在ia[j]，则称(i, j)为a数组的一个逆序对（inversion）。 比如 有5个逆序对。请采用类似“合并排序算法”的分治思路以O(nlogn)的效率来实现逆序对的统计。 一个n个元素序列的逆序对个数由三部分构成： （1）它的左半部分逆序对的个数，（2）加上右半部分逆序对的个数，（3）再加上左半部分元素大于右半部分元素的数量。 其中前两部分（1）和（2）由递归来实现。要保证算法最后效率O(nlogn)，第三部分（3）应该如何实现？ 此题请勿采用O(n^2)的简单枚举算法来实现。 并思考如下问题： （1）怎样的数组含有最多的逆序对？最多的又是多少个呢？ （2）插入排序的运行时间和数组中逆序对的个数有关系吗？什么关系？ 输入格式 第一行：n，表示接下来要输入n个元素，n不超过10000。 第二行：n个元素序列。 输出格式 逆序对的个数。 输入样例 5 2 3 8 6 1 输出样例 5(Set a[0... N-1] is a n array containing n numbers. If there is a [i] > a [j] i n the case of I < j, then (i, j) is a n inversion pair of a array. For example, has five reverse pairs. Please use the idea of "merge sorting algorithm" to achieve the statistics of inverse pairs with O (nlogn) efficiency. The number of inverse pairs of a sequence of n elements consists of three parts: (1) The number of reverse pairs in the left half, (2) the number of reverse pairs in the right half, (3) the number of elements in the left half is greater than that in the right half. The first two parts (1) and (2) are implemented by recursion. To ensure the final efficiency of the algorithm O (nlogn), how should the third part (3) be implemented? Do not use O (n ^ 2) simple enumeration algorithm to solve this problem.)