R help - Sep 2001 - Tildes in R docmentation.

I'm getting flummoxed when trying to putting a tilde (``~'') --- as
in a formula --- into an R documentation file, or rather in getting
one to appear in the *.dvi output that results from converting a *.Rd
file.

In my *.Rd file I wrote an expression of the form

	\code{cbind(x,y) ~ z}

This shows up in the appropriate way in the plain text help,
and in the html help.  But if I do

	R CMD Rd2dvi foo.Rd

I get hang-ups at the latex processing stage.  I get told

===+===+===+===+===+===+===+===+===+===+===+===+===+===+===+===+===+===+==!
Undefined control sequence.
<argument> cbind(x,y) \textasciitilde 
                                          {} z
l.93 \code{cbind(x,y) \textasciitilde{} z}
===+===+===+===+===+===+===+===+===+===+===+===+===+===+===+===+===+===+==
The documentation on writing documentation tells me that I
should, in ``regular text'' enter ~ as 

	\eqn{\mbox{\textasciitilde}}{~} or \eqn{\sim}{~}

but that no characters other than ``%'' and ``\'' are
``special''
inside verbatim environments such as \code{}.

However the Rd to latex processor seems to be converting the ~
into ``\textasciitilde{}'' --- with a pair of braces on the end
as if there should be an argument to the control sequence.  And
then latex is unable to find that control sequence.

Can anyone explain to me what's going on, and how to go about
solving the problem?

Is this a bug, or am I doing something wrong?  Presumably
``\textasciitilde'' ought to be lurking about somewhere, but
it ain't lurking about on our system.  Where could I get it?
I.e. what latex package or *.sty file would it be found in,
and where would that package/*.sty file be located?

Thanks.

					cheers,

						Rolf Turner
						rolf at math.unb.ca
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This is widely used in the system help files. See e.g lm.Rd which has
\code{response ~ terms}.

That works in text, html and latex (how do you think we get a reference
manual made?).

\textasciitilde is a standard part of latex (in file latex.ltx).  The
feature was introduced in the 1995/12/01 release (see the usrguide.tex) so
it looks as if your latex is more than 5 years' old, or broken.

[...]
> However the Rd to latex processor seems to be converting the ~
> into ``\textasciitilde{}'' --- with a pair of braces on the end
> as if there should be an argument to the control sequence.  And
> then latex is unable to find that control sequence.
That's not what {} means.  It's an empty token to escape the following
space.  (la)tex does not use {} to introduce arguments.
> Can anyone explain to me what's going on, and how to go about
> solving the problem?
You do need a reasonably recent fully functional latex system.  Probably no
more than a couple of years' old (we don't have ancient installations
around to test).

[...]


-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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