Just to add a small note, sin(pi) is below machine precision : > .Machine$double.eps [1] 2.220446e-16
(see ?.Machine for exact definition) -> if myval is bounded to be positive, one safe way of testing equality to 0 would then be "myval < .Machine$double.eps" On Thu, Sep 26, 2013 at 2:48 PM, Suzen, Mehmet <msu...@gmail.com> wrote: > On 26 September 2013 11:30, Rainer M Krug <rai...@krugs.de> wrote: > >>>> Why doesn't return me 0? > > It isn't R question at all. You might want to read about representing > real numbers in a computer using floating point > http://en.wikipedia.org/wiki/Floating_point > > If you want more precision for some reason, you may want to use Rmpfr > package from CRAN, for example > > require(Rmpfr) > > pii <- mpfr(pi, 1200) > > sin(pii) > 1 'mpfr' number of precision 1200 bits > [1] > 1.22464679914735317722606593227499799708305390129979194948825771626086960997325810377509325527569013655456428540074414189136673810003656057935764118217436637676835016019778833613838580470703060741630570066750947925902443295873487819032259435513861185501796412843027607796970259523768923503206248925733373776859085615900203929142965774524665617260404787862664073939e-16 > > > > | > Is that a Fortune? And, if so, should R be using computers? > > Don't blame R for real numbers. > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
