Floating point multiplication in python

Chris Rebert clp2 at rebertia.com
Tue Sep 6 08:18:30 CEST 2011


On Mon, Sep 5, 2011 at 10:57 PM, xyz <xyzhtml at 163.com> wrote:
> hi all:
>
> As we know ,  1.1 * 1.1 is 1.21 .
> But in python ,I got following :
>
>>>> 1.1 * 1.1
> 1.2100000000000002
>
> why python get wrong result?

It's not Python's fault per se, rather it's the inherent nature of
binary floating-point arithmetic. Try the equivalent in most other
languages and you'll get the same "error".
Please read http://docs.python.org/tutorial/floatingpoint.html

Cheers,
Chris



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