Hi Maja, Values that are theoretically the same may not be exactly identical when using floating point arithmetic. Please read this FAQ page:
http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-doesn_0027t-R-think-these-numbers-are-equal_003f If you need to test that they are "equal", you may add a tolerance (say, for example, are they equal within 1e-8) Cheers, Josh On Thu, Mar 10, 2011 at 7:18 AM, maiya <maja.zaloz...@gmail.com> wrote: > Hi there! > I'm not sure I can create a minimal example of my problem, so I'm linking to > a minimal .RData file that has only two objects: obs and exp, each is a 6x9 > matrix. http://dl.dropbox.com/u/10364753/test.RData link to dropbox file > (I hope this is acceptable mailing list etiquette!) > > Here's what happens: >> obs[1, 1] > [1] 118 >> exp[1, 1] > [1] 118 >> obs[1, 1]-exp[1, 1] > [1] 2.842171e-14 > > Problem is, both obs and exp should be identical. They are the result of a > saturated loglinear model, and I've run the same code across about 400 > tables, all of which result in sum(obs-exp)=0, except for this one. I can't > figure it out? > > Anyway, I need help understanding why 118 and 118 are not really the same. I > appreciate some may be wary of downloading my .Rdata file (I'm on ubuntu if > that's any consolation), but I don't know how else to ask this quesiton! > > Thanks! > > Maja Z. > > > > -- > View this message in context: > http://r.789695.n4.nabble.com/identical-values-not-so-identical-newbie-help-please-tp3346078p3346078.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. > -- Joshua Wiley Ph.D. Student, Health Psychology University of California, Los Angeles http://www.joshuawiley.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.
