http://neuralnetworksanddeeplearning.com/chap1.html
Theano
http://deeplearning.net/software/theano/tutorial/python.html#
Python
https://www.liaoxuefeng.com/wiki/0014316089557264a6b348958f449949df42a6d3a2e542c000
原文：https://www.cnblogs.com/jukan/p/9090086.html