On Thu, 15 May 2008, Barry Rowlingson wrote:
Duncan Murdoch wrote:
It's fairly unlikely to go away, but it's an old undocumented feature, so
use at your own risk. There are lots of other undocumented features, but
maybe no others at the lexical level. Check out src/main/gram.y if you
want to search for more at that level, and src/* if you want them at any
level.
I just had a quick browse in the source and I can't see where "**" is
defined. names.c relates ^ to the power operation in arithmetic.c but no sign
of "**":
./names.c:{"^", do_arith, POWOP, 1, 2, {PP_BINARY2,
PREC_POWER, 1}},
grepping for POWOP doesn't help.
It's not an operator like '*':
get("**")
Error in get("**") : variable "**" was not found
get("*")
function (e1, e2) .Primitive("*")
and there's no ** in gram.y.
searching for 'power' and quoted "**" doesn't help me either. Searching for
unquoted ** just produces too much C code to be useful.
It's got to be there somewhere!!!
Is there a clue in:
"^"(5, 2)
[1] 25
"**"(5, 2)
Error: could not find function "**"
5 ^ 2
[1] 25
5 ** 2
[1] 25
that is, it is truly obfuscated and not accessible using contemporary
interfaces?
Roger
Barry
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
--
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: [EMAIL PROTECTED]
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
