#反向传播算法#     

反向传播算法对于快速训练大型神经网络来说至关重要。google的讲解：
https://google-developers.gonglchuangl.net/machine-learning/crash-course/backprop-scroll/">https://google-developers.gonglchuangl.net/machine-learning/crash-course/backprop-scroll/