在运行前添加这一句
addpath(genpath(pwd));
pwd：当前工作目录
current working directory
genpath：返回指定目录及其所有子目录所组成的字符串
returns a path string starting in D, plus, recursively,
all the subdirectories of D, including empty subdirectories.
addpath:将路径添加到搜索目录
prepends all the specified directories to
the path
