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%%  Ein Beispiel der DANTE-Edition
%%  Mathematiksatz mit LaTeX
%%  3. Auflage
%%  Beispiel 11-04-2 auf Seite 243.
%%  Copyright (C) 2018 Herbert Voss
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%%  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.
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\documentclass[10pt,a5paper]{exaarticle2}
\pagestyle{empty}
\setlength\textwidth{170.40707pt}
\setlength\parindent{0pt}
%StartShownPreambleCommands
\usepackage{mathspec}
\setmainfont{libertinusserif-regular.otf}
\setmathsfont(Digits,Latin,Greek)
 [Numbers={Lining,Proportional},
  Mapping=tex-text]{LucidaBrightMathOT}
%StopShownPreambleCommands
\begin{document}
\textit{Pythagoras:}
\[ \int\limits_1^{\infty}
  \frac1{\alpha^2}\mathrm d\alpha=1 \]
\end{document}