Softmax回归推导过程 http://www.cnblogs.com/Deep-Learning/p/7073744.html http://www.cnblogs.com/lutingting/p/4768882.html http://chenrudan.github.io/blog/2016/01/09/logisticregression.html http://www.cnblogs.com/Determined22/p/6362951.html http://blog.csdn.net/pandav5/article/details/51119131