LaTeX Forum

\documentclass[a4paper,10pt]{scrartcl}
\usepackage[utf8]{inputenc}

\usepackage{amsmath}

%opening
\title{Ein Titel}
\author{Der Author}

\begin{document}

\maketitle

\begin{abstract}

\end{abstract}

\section{Test}

\begin{equation}
\boxed{
\begin{alignat}{4}
  \frac{\partial{a}_{1}}{\partial{t}} &= \frac{\partial^{2}{b_{M}\zeta_{1}}}{\partial{c^{2}}}+f\zeta_{2} 
  \hspace{2cm} \text{und}
  &\frac{\partial{a}_{2}}{\partial{t}}& &&= \frac{\partial^{2}{b_{M}\zeta_{2}}}{\partial{c^{2}}}+f\zeta_{1} \\
%   
  \zeta_{1} &= \frac{\partial^{2}\psi_{1}}{\partial{z^{2}}}
  \hspace{2cm} \text{und}
  &\zeta_{2}& &&= \frac{\partial^{2}\psi_{2}}{\partial{z^{2}}} \\
%
  u &= \frac{\partial\psi_{2}}{\partial{z}} 
  \hspace{2cm} \text{und}
  &v& &&= -\frac{\partial\psi_{1}}{\partial{z}} \\
%
  K_{M} &= (\kappa{z})^{2}\sqrt{\zeta_{1}^{2}+\zeta_{2}^{2}}
\end{alignat}
}
\end{equation}


\end{document}

\begin{equation}
    \boxed{
        \begin{alignat}{5}
            \frac{\partial{a}_{1}}{\partial{t}} &= \frac{\partial^{2}{b_{M}\zeta_{1}}}{\partial{c^{2}}}+f\zeta_{2}
            \hspace{0.5cm} &\text{und}& \hspace{0.5cm}
            &\frac{\partial{a}_{2}}{\partial{t}}& &&= \frac{\partial^{2}{b_{M}\zeta_{2}}}{\partial{c^{2}}}+f\zeta_{1} \\
%  
            \zeta_{1} &= \frac{\partial^{2}\psi_{1}}{\partial{z^{2}}}
            \hspace{0.5cm} &\text{und}& \hspace{0.5cm}
            &\zeta_{2}& &&= \frac{\partial^{2}\psi_{2}}{\partial{z^{2}}} \\
%
            u &= \frac{\partial\psi_{2}}{\partial{z}}
            \hspace{0.5cm} &\text{und}& \hspace{0.5cm}
            &v& &&= -\frac{\partial\psi_{1}}{\partial{z}} \\
%
            K_{M} &= (\kappa{z})^{2}\sqrt{\zeta_{1}^{2}+\zeta_{2}^{2}}
        \end{alignat}
    }
\end{equation}