浮点数运算的问题

0.1+0.2=0.30000000000000004的问题

http://www.cnblogs.com/jillzhang/archive/2007/06/24/793901.html

http://justjavac.iteye.com/blog/1724438

http://geeklu.com/2011/03/ieee754-floating-point-arithmetic/

http://floating-point-gui.de/