\usepackage{xltxtra}
\usepackage{pbox}
\usepackage{mathtools}
\usepackage{amssymb}
\usepackage{tabularx}
\usepackage{siunitx}
\usepackage{unicode-math}
\usepackage[top=13pt, bottom=12pt, left=13pt, right=12pt]{geometry}
% \setromanfont[Mapping=tex-text]{Linux Libertine O}
% \setsansfont[Mapping=tex-text]{DejaVu Sans}
% \setmonofont[Mapping=tex-text]{DejaVu Sans Mono}

\title{}
\author{}
\date{}

\let\oldcdot\cdot
\let\oldbullet\bullet
\let\oldvec\vec
\let\olddot\dot
\let\oldddot\ddot

% \renewcommand{\cdot}{ }
\renewcommand{\bullet}{\circ}
% \renewcommand{\vec}{\mathbf}
% \renewcommand{\dot}[1]{\frac{\mathrm{d}#1}{\mathrm{d}t}}
% \renewcommand{\ddot}[1]{\frac{\mathrm{d^2}#1}{\mathrm{d}t^2}}
% \renewcommand{\frac}[2]{#1 / #2}
\newcommand{\cdotbis}{ }

\newcommand{\dif}{\mathrm{d}}

\setlength{\parindent}{0pt}
\setlength{\parskip}{0pt}

% \everymath{\displaystyle}