This is a FAQ: http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-doesn_0027t-R-think-these-numbers-are-equal_003f and also covered nicely in Burns' R Inferno: www.burns-stat.com/pages/Tutor/R_inferno.pdf
Sarah On Wed, Mar 18, 2009 at 11:58 AM, Yu, Changhong <y...@ccf.org> wrote: > Dear all, > > > > I am totally confused by the following R output, but don't have a clue > for it. > > > >> a <- 1 - 0.2 > >> a == 0.8 > > [1] TRUE > >> a <- 1 - 0.8 > >> a == 0.2 > > [1] FALSE > >> a <- 1 - 0.5 > >> a == 0.5 > > [1] TRUE > >> a <- 1 - 0.6 > >> a == 0.4 > > [1] TRUE > >> a <- 1 - 0.9 > >> a == 0.1 > > [1] FALSE > > > > > > My R version is Windows XP R version 2.8.1 (2008-12-22). > > > > Thanks very much. > > > > > > Changhong > > -- Sarah Goslee http://www.functionaldiversity.org ______________________________________________ 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.
