中文说明：该程序可以对二维三类样本进行分类，并画出分界面．学习过模式识别的人必看．要学习神经网络的人必看，代码简单，实用性强
English Description：
The program can classify three kinds of two-dimensional samples and draw the interface. Those who have learned pattern recognition must see it. Those who want to learn neural network must see it. The code is simple and practical