问题
Possible Duplicate:
Python float - str - float weirdness
Python float division does not appear to have accurate results. Can someone explain why?
>>>3.0/5
0.59999999999999998
回答1:
Short answer: Floats use finite-precision binary encoding to represent numbers, so various operations lose some precision.
The Wikipedia page has a lot of information (maybe too much).
See also: How do I use accurate float arithmetic in Python?
回答2:
Floating point arithmetic is not exact; there are rounding errors that are worsened by the fact that computers use binary floating point and not decimal floating point. See Wikipedia.
来源：https://stackoverflow.com/questions/8120914/python-float-division-not-exact