标签：
http://www.codelast.com/?p=8006
http://www.codelast.com/?p=2573
http://blog.csdn.net/xmu_jupiter/article/details/22220987
http://www.cnblogs.com/jerrylead/archive/2011/03/09/1978280.html
梯度下降
原文地址：http://www.cnblogs.com/yxzfscg/p/4895988.html
