Formatting crystallographic indices

Question

I would like to make a command in LaTeX that can be used like this:

\zoneaxis{1 2 -3}
\zoneaxis{2 -1 -1 10}

and would produce this:

$[1\,2\,\overline{3}]$
$[2\,\overline{1}\,\overline{1}\,10]$

That is, the three or four numbers are set into brackets, any minus signs are set as overlines, and there is a little space between the numbers.

It seems like I would have to get into character-by-character parsing, but I have no idea where to look for how to do that.

Does something like this already exist? If not, where could I find out how to do this?

Answer 1

The miller package is probably what you are looking for. Makes typesetting Miller indices quite easy.

Answer 2

I suggest the use of xstring, which makes the parsing easier:

\documentclass{minimal}
\usepackage{xstring}
\makeatletter
\newcommand\zoneaxis[1]{%
    \begingroup
        \expandarg
        \def\remain@arg{#1 }%
        \ensuremath{[\zoneaxis@]}%
    \endgroup}

\newcommand\zoneaxis@{%
    \StrBefore\remain@arg\space[\current@arg]%
    \StrBehind\remain@arg\space[\remain@arg]%
    \IfBeginWith\current@arg-%
        {\overline{\expandafter\@gobble\current@arg}}%
        \current@arg
    \ifx\@empty\remain@arg\else
        \thinspace\expandafter\zoneaxis@
    \fi}
\makeatother
\begin{document}
$[2\,\overline{1}\,\overline{1}\,10]$

\zoneaxis{2 -1 -1 10}
\end{document}