浮点数的加减计算总结

http://www.tyut.edu.cn/kecheng1/2008/site04/courseware/chapter2/2-2-2-2.html

http://blog.csdn.net/techx/article/details/43830781

http://blog.csdn.net/u011240016/article/details/52623697

http://blog.csdn.net/andkobe/article/details/9534949