中文说明：Matlab的NNbox提供了建立神经网络的专用函数newff().用newff函数来确定网络层数,每层中的神经元数和传递函数,bP网络可以包含不同的隐层,但理论上已经证明,在不限制隐层节点数的情况下,两层(只有一个隐层)的BP网络可以实现任意非线性映射.
English Description：
Nnbox of MATLAB provides a special function newff () to build neural network. Newff function is used to determine the number of network layers, the number of neurons in each layer and the transfer function. BP network can contain different hidden layers, but it has been proved theoretically that BP network with two layers (only one hidden layer) can realize any nonlinear mapping without limiting the number of hidden layer nodes