Fixed bug with multiple authors in pdf output

[robjhyndman]

Fixes #353

[yihui]

Thanks!, But I guess this fixes the symptom (and changes behavior) without curing the disease, and I'd very much like to preserve \and since it is the correct thing to do in LaTeX when writing multiple authors.

[robjhyndman]

I'm not sure what you mean by "correct". The definition of \and is

\def\and{%                  % \begin{tabular}
  \end{tabular}%
  \hskip 1em \@plus.17fil%
  \begin{tabular}[t]{c}}%   % \end{tabular}

This normally works because LaTeX sets the authors within a tabular environment. But rmarkdown uses the titling package which does not use the tabular environment, and then the definition causes a problem.

My fix was just to replace \and with \\\\ which avoids the use of the tabular environment and so it does not cause a clash when the titling package is loaded.

There is some discussion of this issue at https://tex.stackexchange.com/questions/109658/and-command-in-author-tag

[robjhyndman]

Note that I also mimicked the formatting for html and doc outputs which places each author on a new line. Using \and without the titling package will put authors on the same line. Presumably we want the output to be as similar as possible for each output type.

[yihui]

By "correct", I mean \and is what we normally use to separate authors. If you hard-code it to be a line break \\, there is no way to customize it. For example, the original layout was to put authors on one line, and that is what I'd prefer.

@jjallaire I feel we opened a can of worms by defining our own LaTeX template here. I looked at Pandoc's default template again, and the spacing does not look too bad:

---

---

This is what our template produced:

---

---

Anyway, since it is trivially easy to switch to Pandoc's default template in R Markdown, this issue does not really bother me too much.

[jjallaire]

@yihui I hear what you are saying and am certainly tempted to go back to using pandoc's template. I have heard however from a ton of people that they don't like the default pandoc spacing at the top so it wouldn't be without significant detractors. I think we should leave it as-is for now and perhaps make it more obvious (via documentation and the IDE) how to switch to the default template.