On Fri, 17 Nov 2006, Robin Hankin wrote:
>
> OK, I see. But in algebra the "+" symbol is special: it is reserved
> exclusively for associative and commutative operations [thus a+b+c is
> always well-defined]; perhaps the parser could fall in with this
> convention?
>
It's not so long ago that we had a proposal for "+" to implement a
non-associative and non-commutative operation: "+.character" was going to
be string concatenation.
And as Peter pointed out, + is already non-associative under recycling
rules. Type changes are also a problem:
> as.integer(2^30)+as.integer(2^30)+1
[1] NA
Warning message:
NAs produced by integer overflow in: as.integer(2^30) + as.integer(2^30)
> as.integer(2^30)+(as.integer(2^30)+1)
[1] 2147483649
-thomas
______________________________________________
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
