[R] Is this correct?

[Joe]

Dear userR,

With the following results, are they correct or acceptable?

> x <- c(1.4, 1.2, 2.8)
> sum(x)
[1] 5.4
> sum(x) == 5.4
[1] FALSE
> (1.4 + 1.2 + 2.8) - 5.4
[1] -8.881784e-16
> (1.4 + 1.2) - 2.6
[1] -4.440892e-16
> 2.6 - 1.5 - 1.1
[1] 0

> version
         _
platform i386-pc-mingw32
arch     i386
os       mingw32
system   i386, mingw32
status
major    2
minor    2.0
year     2005
month    10
day      06
svn rev  35749
language R

What can I do to correct them if they are not correct?
Thanks!
--
C. Joseph Lu
Department of Statistics
National Cheng-Kung University
Tainan, Taiwan, ROC