Hi Andreas, It's because you are dealing with binary or floating point calculations, not just a few apples and oranges, or an abacus (which, by the way, is an excellent calculating device, and still widely used in some [sophisticated] parts of the world).
http://en.wikipedia.org/wiki/Floating_point HTH, Marks. Kunzler, Andreas wrote: > > Dear List, > > I ran into some trouble by calculating differences. For me it is > important that differences are either 0 or not. > > So I don't understand the outcome of this calculation > > 865.56-(782.86+0+63.85+18.85+0) > [1] -1.136868e-13 > > I run R version 2.71 on WinXP > > I could solve my problem by using > round() > but I would like to know the reason. > Maybe someone can help me? > > Thanx > > ______________________________________________ > 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. > > -- View this message in context: http://www.nabble.com/calculate-differences---strange-outcome-tp18505010p18505498.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.