Same for me on Mac OS X: > x <- c(0.1819711,0.4811463,0.1935151,0.1433675) > 1-sum(x) [1] 0 > version$version.string [1] "R version 2.11.1 Patched (2010-05-31 r52180)"
Regards, Jorge On Tue, Jun 15, 2010 at 6:40 PM, Gabor Grothendieck <> wrote: > On Tue, Jun 15, 2010 at 6:00 PM, Yen Lee <> wrote: > > Hello, everyone, > > > > There's a problem about zero in R and I really need your help. > > > > > > > > I have a vector shown as x=c(0.1819711,0.4811463,0.1935151,0.1433675), > > > > The sum of this vector is shown as 1 in R, but when I type 1-sum(x), the > > value is not zero, but -2.220446e-16. > > > > I can accept that this value is quite small and could be seen as zero, > but > > there would be a problem when it's not really zero but a negative value > in > > my algorithm. > > > > > > > > Therefore I would like to know that how could it be avoid. > > > > One way I think is to define the value 1-sum(x) as zero when it is > smaller > > than a particular value, but the particular value is not be set yet. > > > > I would like to know more about the definition of the shown zero in R. > > > > As others have pointed out please read the R FAQ. > > Actually on my machine: Windows Vista running C2D BLAS, "R version > 2.11.1 Patched (2010-05-31 r52167)" > I do get zero: > > > x <- c(0.1819711,0.4811463,0.1935151,0.1433675) > > 1-sum(x) > [1] 0 > > Also check out sum.exact in the caTools package. > > ______________________________________________ > 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.
