%%
%% The LaTeX Companion, 2ed (second printing August 2004)
%%
%% Example 8-4-10 on page 494.
%%
%% Copyright (C) 2004 Frank Mittelbach, Michel Goossens,
%%    Johannes Braams, David Carlisle, and Chris Rowley
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3
%% of this license or (at your option) any later version.
%%
%% See http://www.latex-project.org/lppl.txt for details.
%%

\documentclass{ttctexa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{111.0pt}

%
% there is a bug in the amsmath macros for ddd and dddd dots which the
% AMS intends to fix as follows (we already anticipated that fix
% here, though it isn't quite right yet for all cases):
%
\makeatletter
\AtBeginDocument{% we have to be after amsmath is loaded in the example
 \renewcommand{\dddot}[1]{%
  {\mathop{\kern\z@#1}\limits^{\vbox to-1.4\ex@{\kern-\tw@\ex@
   \hbox{\,\normalfont...}\vss}}}}
 \renewcommand{\ddddot}[1]{%
  {\mathop{\kern\z@#1}\limits^{\vbox to-1.4\ex@{\kern-\tw@\ex@
   \hbox{\,\normalfont....}\vss}}}}
 }
\makeatother

\StartShownPreambleCommands
\usepackage{amsmath}
\StopShownPreambleCommands
\begin{document}
$ \dot{S} \quad \ddot{P} \quad \dddot{Q} \quad \ddddot{R} $
\end{document}
