[Tex/LaTex] “Long” Up Down Arrow

Question

The traditional \Updownarrow is short. However, I want a "long" \Updownarrow. Does it exist? What package should I seek?

Answer 1

The size of the \Updownarrow symbol can be increased (almost) arbitrarily by placing it inside a pair of \left...\right directives. Moreover, as @egreg points out in a comment, \big\Updownarrow through \Bigg\Updownarrown is available as well.

\documentclass{article}
\usepackage[intlimits]{amsmath}
\begin{document}
$\Updownarrow$
$\displaystyle\left\Updownarrow\vphantom{\int}\right.$
$\displaystyle\left\Updownarrow\vphantom{\int_A^B}\right.$
\end{document}