R. Michael Weylandt
michael.weylandt at gmail.com
Sat Jan 5 19:48:48 CET 2013
On Sat, Jan 5, 2013 at 6:42 PM, David Arnold <dwarnold45 at suddenlink.net> wrote:
> Can someone explain this:
>  0.33333333333333331483
> Why the 1483 at the end?
To be curt, "it's complicated," but it basically comes down to the
fact that 1/3 is not expressible by a finite sequence of powers of 2
so it can't be perfectly represented in binary.
This is (one of many examples of) a nastyness due to floating-point
representation. See R FAQ 7.31 and the documents linked therein for a
comprehensive tutorial, but "floating point error" should be enough to
guide your googling.
> david-arnolds-macbook-pro-2:~ darnold$ R --version
> R version 2.15.2 (2012-10-26) -- "Trick or Treat"
> Copyright (C) 2012 The R Foundation for Statistical Computing
> ISBN 3-900051-07-0
> Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)
> View this message in context: http://r.789695.n4.nabble.com/Rounding-tp4654738.html
> Sent from the R help mailing list archive at Nabble.com.
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> and provide commented, minimal, self-contained, reproducible code.
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