> x <- 1.00000001 > all.equal(x, 1) [1] TRUE > x == 1 [1] FALSE
Reading help(all.equal) will tell you that the tolerance level by default is around 1.490116e-08. On Fri, 2004-11-05 at 13:48, Kay Pilz wrote: > Hello All. > > I am running R 2.0.0 with a Win XP operating system. The same problem occured > with R 1.9.1 but not with R.1.3.1 on a Win NT computer. So, which version are you having this problem with ? > My request is about the following problem with the sort function: > > The vector price is a vector of 789 asset prices of the following form, > > > mode(price) > [1] "numeric" > > price[1:10] > [1] 1.1315 1.1314 1.1313 1.1314 1.1315 1.1316 1.1315 1.1317 > [9] 1.1316 1.1316 > > Then the returns are defined to be the differences, > > > ret <- diff(price) > > ret[1:10] > [1] -1e-04 -1e-04 1e-04 1e-04 1e-04 -1e-04 2e-04 -1e-04 > [9] 0e+00 0e+00 > > Here R recognizes the first two entries and also the second ones to be equal > (I did not found any two equal entries, where R didnt recognized this > relation), > > > ret[1]==ret[2] > [1] TRUE > > ret[3]==ret[4] > [1] TRUE > > But after sorting the vector, this ist not longer true, > > > s <- sort(ret) > > s[1:10] > [1] -5e-04 -5e-04 -5e-04 -5e-04 -5e-04 -4e-04 -4e-04 -4e-04 > [9] -4e-04 -4e-04 > > s[1]==s[2] > [1] FALSE > > Taking the difference of the first two entries yields > > > s[1]-s[2] > [1] -2.220446e-16 > > which seems to be a numerical artefact. > > Is this a bug, or just a handling error by me? > > Thanks a lot for your answers, > Kay Frederik Pilz > Ruhr-Universitaet Bochum > Germany > [EMAIL PROTECTED] > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html