For EPSILON, you can use the constants FLT_EPSILON, which is defined for float as 1.192092896e-07F, or DBL_EPSILON, which is defined for double as 2.2204460492503131e-016.

• 对于EPSILON；可以使用常数FLT_EPSILON(为浮点型定义为1.；192092896e-07F)或者DBL_EPSILON(为双精度型定义为2