%% %% Der Mathematiksatz mit LaTeX, 1. Auflage 2009 %% %% Example 6-15-2 on page 125. %% %% Copyright (C) 2009 Herbert Voss %% %% It may be distributed and/or modified under the conditions %% of the LaTeX Project Public License, either version 1.3 %% of this license or (at your option) any later version. %% %% See http://www.latex-project.org/lppl.txt for details. %% \documentclass[]{ttctexa} \pagestyle{empty} \setcounter{page}{6} \setlength\textwidth{355.65944pt} \usepackage[utf8]{inputenc} \AtBeginDocument{\setlength\parindent{0pt}} \StartShownPreambleCommands \usepackage{amsmath} \makeatletter \newcommand\xLongLeftRightArrow[2][]{\ext@arrow 0055{\LongLeftRightArrowfill@}{#1}{#2}} \def\LongLeftRightArrowfill@{\arrowfill@\Leftarrow\Relbar\Rightarrow} \newcommand\xlongleftrightarrow[2][]{\ext@arrow 0055{\longleftrightarrowfill@}{#1}{#2}} \def\longleftrightarrowfill@{\arrowfill@\leftarrow\relbar\rightarrow} \makeatother \StopShownPreambleCommands \begin{document} $\Leftarrow\Relbar\Rightarrow$ $\Leftarrow\mkern-3mu\Relbar\mkern-3mu\Rightarrow$ $\xLongLeftRightArrow[\text{UUU}]{\text{OOOOOOO}}$ $\xlongleftrightarrow[y=f(x,v,w)]{x=f(w)}$ \end{document}