# How to make a vertical \iff?

I will like to make a vertical version of \iff. I can not be satisfied with \Updownarrow, as it is too short.

\Updownarrow is an extensible symbol, so you can use \Big in front of it.

\documentclass{article}
\usepackage{amsmath}

\newcommand{\Longupdownarrow}{\Big\Updownarrow}

\begin{document}

\begin{align*}
a+b&=c \\
\Longupdownarrow \\
x+y&=z
\end{align*}

\end{document}


• Wow! This is the simplest way. The example you have written is actually have I want to use it! 👏🏼 Bravo – Xenusi Oct 27 '19 at 19:23

You can do that with a \rotatebox:

\documentclass[11pt]{report}
\usepackage[utf8]{inputenc}
\usepackage{amssymb}
\usepackage{graphicx}

\begin{document}

$A\mathrel{\mkern 3mu\rotatebox[origin =c]{90}{\iff}}B$%

\end{document}


Edit: as suggested by @egreg, you might consider using \Longleftrightarrow, which has a different spacing on each side (i.e. above and below after rotation):

\documentclass[11pt]{report}
\usepackage[utf8]{inputenc}
\usepackage{amsmath, amssymb}
\usepackage{graphicx}

\begin{document}

\begin{gather*}
xxx yyyy zzz \\
A\mathrel{\mkern 3mu\rotatebox[origin =c]{90}{$\iff$}}B \\
xxx yyyy zzz \\
A\mathrel{\mkern 3mu\rotatebox[origin =c]{90}{$\Longleftrightarrow$}}B \\
xxx yyyy zzz%
\end{gather*}

\end{document}


• Probably \Longrightarrow is better than \iff, which adds spaces on either side (so above and below when rotated). – egreg Oct 27 '19 at 19:18