It's imprecision of floating point representation of real numbers: > print(abs(.7 - .5) - abs(.3 - .5), digit=20) [1] -5.551115123125783e-17
one of the first things to learn about programming: be extremely careful testing for equality of floating point numbers. Andy > From: Nathan Leon Pace, MD, MStat > > Hi, > > Using R 2.0.1 on Mac g5 running Mac OS X 10.3.6. > > I would expect that > > abs(.7 - .5) >= abs(.3 - .5) should be returned TRUE. > > Instead > > > www <- abs(.7 - .5) >= abs(.3 - .5) > > www > [1] FALSE > > Is this a result of floating point or the implementation of abs or > something else? > > In a function I need to compare two absolute values - each > being of the > form |variable - constant|. > > Any suggestions for implementing this correctly? > > Nathan > > ______________________________________________ > [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