# [R-pkg-devel] .Rd, LaTeX and Unicode

Martin Maechler m@ech|er @end|ng |rom @t@t@m@th@ethz@ch
Tue Jun 18 16:01:23 CEST 2019

>>>>> Hugh Parsonage
>>>>>     on Tue, 18 Jun 2019 20:03:41 +1000 writes:

> utf8x is deprecated
> https://tex.stackexchange.com/questions/13067/utf8x-vs-utf8-inputenc#13070

Hmm... interestingly, I've tried quite a few versions of the
above which started in 2011, but had been updated in April 2016 :
https://tex.stackexchange.com/a/203804/7228
from where it seems that

\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}

should be sufficient.  Further, note that from
https://tex.stackexchange.com/a/238135/7228
the {ucs} package should no longer be needed since ca. 2013,
hence your \usepackage[mathletters]{ucs}  would not be needed either.

HOWEVER:  After losing at least half an hour now, trying many
variants I found that the only version that works correctly for
me (with a teTeX / TeXlive version of 2018) is the version
Serguei Sokol proposes (below), including the use of the 'utf8x'
option *and* the 'ucs' package ...

which is pretty surprising after having read the

> On Tue, 18 Jun 2019 at 7:52 pm, Serguei Sokol <serguei.sokol using gmail.com>
> wrote:

>> Hi,
>>
>> I am preparing a package where I would like to use UTF characters in .Rd
>> files. When the LaTeX comes to play, I got well known errors e.g.:
>> ! Package inputenc Error: Unicode character ∂ (U+2202)
>> (inputenc)                not set up for use with LaTeX.
>>
>> It is coherent with what is said on this page
>> https://developer.r-project.org/Encodings_and_R.html :
>> "Since LaTeX cannot handle Unicode we would have to convert the encoding
>> of latex help files or use Lambda (and tell it they were in UTF-8)."

That whole document has been very important and crucial, written
by Prof Brian Ripley  who had worked a *LOT* to bring unicode to R,
-- but it has been written 2004-2005  and indeed, I think it is
probably fair to say that the above sentence no longer applies
to current LaTeX engines (including "simple" pdflatex)... though really,
I'm not the expert here, but I think it's a good point in time
to reconsider how much UTF8 should be allowed/supported in *.Rd files.

One problem: This is (slightly) the wrong mailing list; this would have
been a perfect topic for 'R-devel' (discussing about new
features etc for R) instead....
( but we'd rather keep it here for now.)

Martin Maechler
ETH Zurich and R Core Team

>> But LaTeX can support UTF8 as shown with this small example:

\documentclass{article}
\usepackage[mathletters]{ucs}
\usepackage[utf8x]{inputenc}

\begin{document}
The vorticity ω is defined as $ω = ∇ × u$.
\end{document}

>> I can compile it with my LaTeX without problem. May be you too?
>> So my suggestion would be to place these two lines somewhere in LaTeX
>> header generated by R doc system:
>> \usepackage[mathletters]{ucs}
>> \usepackage[utf8x]{inputenc}
>>
>> Note "utf8x" and not just "utf8" which is crucial for this example.
>> With a hope that it would fix unicode errors from LaTeX.
>>
>> Best,
>> Serguei.