% File: chemarr.sty % Version: 2001/06/22 v1.1 % Author: Heiko Oberdiek % Email: % % Copyright: Copyright (C) 2001 Heiko Oberdiek. % % This program may be distributed and/or modified under % the conditions of the LaTeX Project Public License, % either version 1.2 of this license or (at your option) % any later version. The latest version of this license % is in % http://www.latex-project.org/lppl.txt % and version 1.2 or later is part of all distributions % of LaTeX version 1999/12/01 or later. % % Function: Very often chemists need a longer version % of reaction arrows (\rightleftharpoons) with % the possibility to put text above and below. % Analogous to amsmath's \xrightarrow and % \xleftarrow this package provides the macro % \xrightleftharpoons. % % Requirement: amsmath % Use: LaTeX: \usepackage{chemarr} % \xrightleftharpoons[below]{above} % % History: 2001/06/21 v1.0: % * first public version % 2001/06/22 v1.1: % * documentation fixes % \NeedsTeXFormat{LaTeX2e} \ProvidesPackage{chemarr}% [2001/06/22 v1.1 Chemical reaction arrows (HO)] % \RequirePackage{amsmath} % The package amsmath is needed for the following commands: % \ext@arrow, \@ifnotempty, \arrowfill@ % \relbar, \std@minus % \@ifempty, \@xifempty, \@xp % % In fontmath.ltx \rightleftharpoons is defined with % a vertical space of 2pt. % \newcommand{\xrightleftharpoons}[2][]{% \ensuremath{% \mathrel{% \settoheight{\dimen@}{\raise 2pt\hbox{$\rightharpoonup$}}% \setlength{\dimen@}{-\dimen@}% \edef\CA@temp{\the\dimen@}% \settoheight\dimen@{$\rightleftharpoons$}% \addtolength{\dimen@}{\CA@temp}% \raisebox{\dimen@}{% \rlap{% \raisebox{2pt}{% $% \ext@arrow 0359\rightharpoonupfill@{\hphantom{#1}}{#2}% $% }% }% \hbox{% $% \ext@arrow 3095\leftharpoondownfill@{#1}{\hphantom{#2}}% $% }% }% }% }% } \newcommand*{\leftharpoondownfill@}{% \arrowfill@\leftharpoondown\relbar\relbar } \newcommand*{\rightharpoonupfill@}{% \arrowfill@\relbar\relbar\rightharpoonup } \endinput