8
\documentclass{article}
\begin{document}
\hsize 200pt

%A wonderful serenity has taken possession of my entire soul, like these sweet
%mornings of spring which I enjoy with my whole heart.

\[ e=mc^2 \]
\end{document}

gives me an overfull hbox:

Overfull \hbox (22.0021pt too wide) in paragraph at lines 9--9
[][]

using $$...$$ instead of \[...\] works fine.

Using a soon-to-be-released tool for visual debugging shows me a strange box sticking out to the right:

strangeboxstickingouttotheright

topskip
  • 37,020

2 Answers2

13

Because you changed the TeX primitive \hsize without telling LaTeX you had done so. You should change \linewidth preferably by using a LaTeX display environment construct that keeps all the LaTeX data consistent. Or for the whole document set \textwidth in the preamble.

David Carlisle
  • 757,742
13

LaTeX's \[ refers to \linewidth, not to \hsize. From latex.ltx:

\def\[{%
   \relax\ifmmode
      \@badmath
   \else
      \ifvmode
         \nointerlineskip
         \makebox[.6\linewidth]{}%
      \fi
      $$%%$$ BRACE MATCH HACK
   \fi
}

So you should change \linewidth instead, or redefine \[ using \hsize. Try, and you will see the warning go away.

This shows again that mixing LaTeX and TeX code can sometimes be dangerous. If there's a LaTeX equivalent for a TeX command (or length), I would prefer the LaTeX command when writing LaTeX.

Regarding using the different widths, here's some further advice: Difference between \textwidth, \linewidth and \hsize.

Community
  • 1
Stefan Kottwitz
  • 231,401
  • Arrg, it's me, Mico, once again accidentally downvoting instead of upvoting an answer. Sorry! Please edit your answer a tiny bit to give me chance to change my vote. Thanks. – Mico Feb 22 '12 at 11:25
  • Thanks! I'll delete my comments in a few minutes as they're now irrelevant. :-) – Mico Feb 22 '12 at 12:49