Hrounding error

Aidan aweraw at gmail.com
Wed Jun 18 08:05:33 CEST 2008


cooperq at gmail.com wrote:
> Hi,
> I am new to python.  I was messing around in the interperator checking
> out the floating point handling and I believe I may have found a
> rounding bug:
> 
>>>> 234 - 23234.2345
> -23000.234499999999
> 
> 
> This is not correct by my calculations.
> 
> I am using python 2.5.2 in ubuntu 8.04.  I am wondering if this is a
> known bug, or if I am just not understanding some feature of python.
> Thanks for the help!
> 
> -Cooper Quintin
> http://www.bitsamurai.net


If you need to round before you display the result, I find the following 
works:

 >>> '%.4f' % (234 - 23234.2345)
'-23000.2345'

The %.4f means that the interpolated value will be treated as a float, 
rounded to 4 digits after the decimal point.



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