随机微分方差（SDE）求解程序，详解，有说明，有直接点击运行的代码，代码有讲解，一看就懂，布朗运动模拟实验代码。一学就会直接拿来用。-Stochastic differential equation (SDE) to solve the program, detailed, there are instructions, there is a direct click to run the code, the code has to explain, a look to understand,