floating point woes
mwilson at the-wire.com
Wed Feb 16 06:39:14 CET 2011
Hans-Peter Jansen wrote:
> while I usually cope with the woes of floating point issues, this is
> one, that I didn't expect:
>>>> round(2.385, 2)
> Doesn't the docs say, it's rounded up for this case?
> Values are rounded to the closest multiple of 10 to the power minus n;
> if two multiples are equally close, rounding is done away from 0
> Well, that one is clearly rounding down.
> What's up, eh, down here?
2.385 isn't really 2.385:
Python 2.6.5 (r265:79063, Apr 16 2010, 13:09:56)
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> repr (2.385)
so it correctly rounded down. You need to use Decimal numbers if you want
numbers that behave the way they look.
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