% !TeX root = ../main.tex

\begin{notation}

  \begin{notationlist}{2em}
    \item[$\displaystyle a$] The number of angels per unit area
    \item[$\displaystyle N$] The number of angels per needle point
    \item[$\displaystyle A$] The area of the needle point
    \item[$\displaystyle \sigma$] The total mass of angels per unit area
    \item[$\displaystyle m$] The mass of one angel
    \item[$\displaystyle \sum_{i=1}^n a_i$] The sum of $a_i$
  \end{notationlist}

\end{notation}



% 也可以使用 nomencl 宏包

% \printnomenclature

% \nomenclature{$\displaystyle a$}{The number of angels per unit are}
% \nomenclature{$\displaystyle N$}{The number of angels per needle point}
% \nomenclature{$\displaystyle A$}{The area of the needle point}
% \nomenclature{$\displaystyle \sigma$}{The total mass of angels per unit area}
% \nomenclature{$\displaystyle m$}{The mass of one angel}
% \nomenclature{$\displaystyle \sum_{i=1}^n a_i$}{The sum of $a_i$}