R-alpha: var() and missing

[Ross Ihaka]

> var() handles missing values in a very strange way. It is not what the
> documentation says
> > var(c(NA,1:10))
> [1] 0
> > var(1:10)
> [1] 9.166667
> This is because sum() handles NA incorrectly
> > sum(NA)
> [1] 0
> > sum(NA,na.rm=T)
> [1] 0
> > sum(NA,na.rm=F)
> [1] 0

This is a bug brought in by changes to complex arithmetic.  I have a
fix and will have a patch (later today I hope).

> Also the documentation gives a pairwise= option to var() which isn't in
> the function.

I think the interpreted front end doesn't match the real back-end.
I'll change it.
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