Double arrow and variable on top

Question

How to create a double arrow line with a variable on its top. Something like this.

Related to https://tex.stackexchange.com/questions/103988/rightarrow-with-text-above-it — BambOo, Sep 06 '18 at 14:12

score 2 · Answer 1 · answered Sep 06 '18 at 14:11

2

Try package mathtools

\documentclass{article}
\usepackage{mathtools}
\begin{document}

$\xleftrightarrow[\text{world}]{\text{hello}}$

\end{document}

answered Sep 06 '18 at 14:11

BambOo

instead \xleftrightarrow... according to op question should be \xLeftrightarrow ... – Zarko Sep 06 '18 at 14:15
@Zarko Really? Doesn't double just mean (here) that there should be arrow heads on both sides? – Sep 06 '18 at 14:16
@marmot, hm, you are probably right ... question is not very clear to me :-( – Zarko Sep 06 '18 at 14:18
@Zarko, I agree the question is maybe unclear but I tried the closest match to the picture :) – BambOo Sep 06 '18 at 14:32

score 1 · Answer 2 · answered Sep 06 '18 at 14:13

1

With \overset:

\documentclass[border=2mm]{standalone}

\usepackage[]{amsmath}

\begin{document}
$
  \overset{n_S^i}{\leftrightarrow}
$
\end{document}

answered Sep 06 '18 at 14:13

Skillmon

2 Answers2