See the FAQ Q7.31: 0.07 is not exactly representable on your computer.
0.060 + 2*0.005 != 0.070 in computer arithmetic:
> options(digits=18)
> 0.060
[1] 0.06
> 0.070
[1] 0.070000000000000007
> 0.060+2*0.005
[1] 0.06999999999999999
> 0.06+2*0.005 -0.07
[1] -1.3877787807814457e-17
> .Machine$double.eps * 0.07
[1] 1.5543122344752193e-17
On Wed, 30 Aug 2006, [EMAIL PROTECTED] wrote:
> Full_Name: Mark James Kelly
> Version: 2.3.1
> OS: Windows
> Submission from: (NULL) (193.63.127.224)
>
>
> Sequence produces slightly inaccurate results.
sequence() is a different function in R.
> #This (supposedely) creates a sequence 0.060,0.065,0.070.....0.30
> thingnor=(seq(0.06,0.30,by=0.005))
>
> #This does the same but rounds to three decimals
> thingrou=round(seq(0.06,0.30,by=0.005),3)
>
> #This is another vector, the same length as the two above, with 24 zeroes,
> then
> 0.070, then 24 zeroes
> otherthing=c(rep(0,24),0.070,rep(0,24))
>
>
> #This fails to select the entries equal to 0.070
> otherthing[otherthing==thingnor[3]]
>
> #This gives the correct answer
> otherthing[otherthing==thingrou[3]]
>
>
> #This compares the two sequences (which should be identical)
> (thingnor-thingrou)
Not according to FAQ Q7.31 and help("==").
--
Brian D. Ripley, [EMAIL PROTECTED]
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
