%% 
%%  Der Mathematiksatz mit LaTeX, 1. Auflage 2009
%% 
%%  Example 4-20-6 on page 73.
%% 
%%  Copyright (C) 2009 Herbert Voss
%% 
%%  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{355.65944pt}
\AtBeginDocument{\setlength\parindent{0pt}}
\StartShownPreambleCommands
\newcommand*\diff{\mathop{}\!\mathrm{d}}
\StopShownPreambleCommands
\begin{document}
\[ ay^\prime=a\frac{\diff y}{\diff x} \quad c\cdot v =  c\,\frac{\diff s}{\diff t} \quad
  a = \frac{\diff{^2t}}{\diff{t^2}} \quad \int\!\!\diff y=\int\!\sin(x)\diff x \]
\end{document}