Re: [R] problem with sum function

2012-03-02 Thread Greg Snow
Others explained why it happens, but you might want to look at the zapsmall function for one way to deal with it. On Thu, Mar 1, 2012 at 2:49 PM, Mark A. Albins wrote: > Hi! > > I'm running R version 2.13.0 (2011-04-13) > Platform: i386-pc-mingw32/i386 (32-bit) > > When i type in the command: > >

Re: [R] problem with sum function

2012-03-01 Thread Petr Savicky
On Thu, Mar 01, 2012 at 04:55:55PM -0500, Sarah Goslee wrote: > Of course there's rounding error: your computer can't > store those decimal numbers precisely. See R FAQ 7.31 for > details. > > See also: > sum(10*c(-0.2, 0.8, 0.8, -3.2, 1.8)) / 10 Hi. This is 0. This works without rounding for on

Re: [R] problem with sum function

2012-03-01 Thread Petr Savicky
On Thu, Mar 01, 2012 at 01:49:44PM -0800, Mark A. Albins wrote: > Hi! > > I'm running R version 2.13.0 (2011-04-13) > Platform: i386-pc-mingw32/i386 (32-bit) > > When i type in the command: > > sum(c(-0.2, 0.8, 0.8, -3.2, 1.8)) > > R returns the value: > > -5.551115e-17 > > Why doesn't R retu

Re: [R] problem with sum function

2012-03-01 Thread William Dunlap
In base ten, using any fixed number of digits, compute 1/3 + 1/3 + 1/3 (doing the divisions before the additions). Why isn't it 1? 1/5 has the same sort of problem in base two. Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > -Original Message- > From: r-help-boun...@r-projec

Re: [R] problem with sum function

2012-03-01 Thread Sarah Goslee
Of course there's rounding error: your computer can't store those decimal numbers precisely. See R FAQ 7.31 for details. See also: sum(10*c(-0.2, 0.8, 0.8, -3.2, 1.8)) / 10 Sarah On Thu, Mar 1, 2012 at 4:49 PM, Mark A. Albins wrote: > Hi! > > I'm running R version 2.13.0 (2011-04-13) > Platform