To be more precise, the decimal number 0.1 does not have an exact binary equivalent. A long time ago, there was a book called, IIRC, "Pascal with Style" or something of that ilk, which set out the warning "Never compare floating point numbers for equality."
-- M. Edward (Ed) Borasky mailto:[EMAIL PROTECTED] http://www.borasky-research.net "Suppose that tonight, while you sleep, a miracle happens - you wake up tomorrow with what you have longed for! How will you discover that a miracle happened? How will your loved ones? What will be different? What will you notice? What do you need to explode into tomorrow with grace, power, love, passion and confidence?" -- L. Michael Hall, PhD > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Uwe Ligges > Sent: Monday, July 14, 2003 1:10 AM > To: Marc Vandemeulebroecke > Cc: [EMAIL PROTECTED] > Subject: Re: [R] bug? > > > 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 > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo> /r-help > ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
