# [Rd] Re: Precedence of %% (PR#879)

**p.dalgaard@biostat.ku.dk
**
p.dalgaard@biostat.ku.dk

*Fri, 20 Apr 2001 14:48:33 +0200 (MET DST)*

This message from Duncan M. (listed below) seems to have escaped the
r-devel list, possibly due to lack of a subject header.
gram.y has
...
%left '*' '/' '%'
%left SPECIAL
%left ':'
...
and %% is a SPECIAL token, so it does indeed have higher precedence
than *. This is somewhat unusual compared to other languages, but it
is compatible with S-PLUS 3.4, so I'd say that it is the documentation
that is wrong. (And that part was written by me, I'm afraid...)
-p
Date: Sun, 18 Mar 2001 07:45:13 -0500 (EST)
From: Duncan Murdoch <murdoch@stats.uwo.ca>
To: r-bugs@r-project.org
According to the documentation (R-lang p. 56), *
and %% (mod) have equal operator precedence, so they
should group from left to right. Thus
3 * 4 %% 5
should give 2, i.e. (3*4) mod 5. However, I get
> 3 * 4 %% 5
[1] 12
i.e. 3 * (4 mod 5).
Other experiments suggest to me that %% is given
higher priority than *, it's not the "left to right"
rule that is not being followed.
Duncan Murdoch
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk) FAX: (+45) 35327907
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