[Numpy-discussion] Rounding the decimal part of a real number
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 : np.round(1.23456789, 3)
> Out: 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 : "%.3f"%np.round(1.23456789, 3)
> Out: '1.235'
> HTH, Chris
> Christopher Barker, Ph.D.
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J R F, IIT DELHI
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