说明：  指出了newff函数新旧版本使用上的区别,并通过选用BP神经网络中多种常见的训练函数分别进行实验,比较这些不同的训练函数对数字分类识别的效果。
(The differences between the old and new versions of the newff function are pointed out, and a variety of common training functions in the BP neural network are used for experiments to compare the effects of these different training functions on digital classification recognition.)