# [Numpy-discussion] Rounding the decimal part of a real number

dileep kunjaai dileepkunjaai at gmail.com
Thu Apr 7 02:36:02 EDT 2011

```Thank you sir...........  thank you very much.............

On Wed, Apr 6, 2011 at 9:36 PM, Christopher Barker <Chris.Barker at noaa.gov>wrote:

> On 4/6/11 6:24 AM, Alan G Isaac wrote:
> > http://docs.scipy.org/doc/numpy/reference/generated/numpy.round_.html
>
> simple enough, of course, but just to be clear:
>
> In [108]: np.round(1.23456789, 3)
> Out[108]: 1.2350000000000001
>
> so the number is rounded to the requested number of decimal places, but
> then stored in a binary floating point format, which may not be able to
> exactly represent that rounded number -- hence the "1" at the end. This
> is simply how floating point works.
>
> and that slight difference _probably_ doesn't matter, but it's worth
> being aware of, because is does make a difference occasionally.
>
> python has a decimal type that can work with exact decimal numbers --
> numpy doesn't support that, as there is no hardware support for it (at
> least on most platforms).
>
> If you want to display it differently, you can use the string formatters:
>
> In [110]: "%.3f"%np.round(1.23456789, 3)
> Out[110]: '1.235'
>
> HTH, Chris
>
>
> --
> Christopher Barker, Ph.D.
> Oceanographer
>
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>
> Chris.Barker at noaa.gov
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>

--
DILEEPKUMAR. R
J R F, IIT DELHI
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