On Mon, 2003-07-14 at 03:10, Uwe Ligges wrote: > Marc Vandemeulebroecke wrote: > > > Dear R programmers, > > > > is there a sensible explanation for the following behaviour? The second > > command seems not to be interpreted correctly. > > > > > >>seq(0.6, 0.9, by=0.1) == 0.8 > > > > [1] FALSE FALSE TRUE FALSE > > > >>seq(0.7, 0.9, by=0.1) == 0.8 > > > > [1] FALSE FALSE FALSE > > > >>c(0.7, 0.8, 0.9) == 0.8 > > > > [1] FALSE TRUE FALSE > > > >>seq(0.9, 0.7, by=-0.1) == 0.8 > > > > [1] FALSE TRUE FALSE > > > > I am running R version 1.7.1 on XP and NT. > > > > Thanks, > > Marc > > > > -- > > > > ______________________________________________ > > [EMAIL PROTECTED] mailing list > > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > > > It is correct, just an instability of the representation of that > floating point number, because (regularly) floating point numbers cannot > be represented exactly. > > Uwe Ligges
An good online reference for these issues is at: http://grouper.ieee.org/groups/754/ Specifically, the article by David Goldberg entitled "What Every Computer Scientist Should Know about Floating-Point Arithmetic", which is listed toward the bottom of that page. HTH, Marc Schwartz ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
