Variance for Vector of Constants is Not Zero

Barry Zajdlik wrote:

Hi All,

An annoying but not critical problem I am having is that the variance 
of
a vector of constants is reported as > 0. I imagine there is a simple
workaround for the following but could not find it after having spent 
an
embarrassing amount of time.

In Splus:

x<-rep(0.02,10)
var(x)
0

In R:

x<-rep(0.02,10)
var(x)
1.337451e-35

Which version of R and which OS is this? I get 0 for both Linux and
Windows with R-2.2.1.
Anyway, 0.02 is not well representable and hence can be very well the
cause for such a numerical inaccuracy.

I assumed the problem had to do with machine precision and suitably
modified .Machine$double.eps and .Machine$double.neg.eps which I 
thought
would fix the problem but without success. Any pointers to a solution
would be appreciated!

Changing .Machine$double.eps does not help to calculate more accurate 
...

Uwe Ligges

Cheers,
Barry Zajdlik