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糊涂先生给他的五个朋友写信，他写了五封信，但是当他的朋友收到信后，都告诉他：“你的信寄错了”。那么请你计算一下：出现这种情况的概率有多少？（假设糊涂先生是随机地往信封里装信的），你能不能把所有的情况都列出来呢(Mr. foolish to write him five friends, he wrote five letters, but when his friend received a letter, told him: )

盒维数计算和豪斯多夫维数的计算与应用研究程序(box counting)

线性规划中的单纯形法的c实现，代码有测试类，(Simplex method for linear programming)

一圆形游泳池如图所示，现在需在其周围建一圆形过道，并在其四周围上栅栏。 栅栏价格为35元/米，过道造价为20元/平方米。 过道宽度为3米， 游泳池半径由键盘输入。 要求编程计算并输出过道和栅栏的造价。(A circular pool as shown in figure, now in its built around to a circular corridor, and in its 4 around on the fence. The fence for 35 yuan/m price, corridor cost for 20 yuan/square metre. Aisle width is 3 meters, The radius of the swimming pool by keyboard input. Demand and output programming calculation of corridor and the cost of the fence. )

模拟波动方程的有限元程序，计算波场快照，有程序说明！(Simulation of the wave equation, the finite element program, calculate the wave field snapshot, procedural instructions)

基于改进的广义S变换，能更好的对数据进行时频分析。(Modified S-transform and its application in data analysis)

四杆桁架结构的有限元分析程序，在VS2008软件中使用C++语言编写，输入为四杆桁架结构的节点坐标，材料参数，边界条件，输出为各节点的应力和应变。(Four-bar truss structure finite element analysis program, the use of C++ written in VS2008 software, input node coordinate the four-bar truss structure, material parameters, boundary conditions, the output of the stress and strain of each node.)

说明：  利用pid算法控制电机转速，转速可调，数码管显示，初学者实用(Using PID algorithm to control motor speed, adjustable speed, digital display, beginners practical)

可以实现十几位整数的四则运算，效率也较好(Four operations can be more than a dozen integer,and the efficiency is better)

这些代码可以用于产生一系列随机数，可以根据需要使用。(These codes can be used to generate a series of random numbers may be used as needed.)