三层前馈神经网络的BP算法。程序具有以下功能：

（1）　　允许选择各层节点数；

（2）　　允许选用不同的学习率η；

（3）　　能对权值进行初始化，初始化用[-1、1]区间的随机数；

（4）允许选用单极性和双极性两种不同Sigmoid型转移函数。

-Three-tier feed-forward neural network BP algorithm. Procedures have the following functions: (1) allows to choose the number of nodes on each floor　(2) allows selection of different learning rate η　(3) be able to initialize the weights, initialized by [-1,1] interval random number　(4) to allow selection of unipolar and bipolar type two different Sigmoid transfer function.