Math & Science ⇒ Flexible Arrow Size

[pallav]

How to increase the size of arrow if (and only if) symbol?

Code: Select all

$a\overset{z_1=z_2+z+3+z_4}\Longleftrightarrow b$

[Stefan Kottwitz]

The mathtools package provides further extensible arrows, such as \xLeftrightarrow:

Code: Select all

\documentclass{article}
\usepackage{mathtools}

\begin{document}
$a \xLeftrightarrow{z_1=z_2+z+3+z_4} b$
\end{document}

Stefan