Hello, everyone, Thank you for all your kindness.
I've solved the problem through your help with the function all.equal. Thank you very much! Yen -----Original Message----- From: Gabor Grothendieck [mailto:ggrothendi...@gmail.com] Sent: Wednesday, June 16, 2010 6:40 AM To: Yen Lee Cc: r-help@r-project.org Subject: Re: [R] Problem about zero On Tue, Jun 15, 2010 at 6:00 PM, Yen Lee <b88207...@ntu.edu.tw> 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.
