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How can I label $\rightleftarrows$ above the top arrow and below the bottom arrow?

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5 Answers 5

20

I don't know which package defines \rightleftarrows but this shows how to get labels over and under one of the standard arrows.

Edit updated to use the requested arrow

\documentclass{article}

\usepackage{amssymb}

\begin{document}

\[a \mathrel{\mathop{\rightleftarrows}^{\mathrm{over}}_{\mathrm{under}}} b\]

\end{document}

enter image description here

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  • 1
    That would be amssymb.
    – percusse
    Commented Apr 8, 2012 at 11:01
  • 1
    @percusse ah thanks I should have known that:-) updated answer Commented Apr 8, 2012 at 11:10
  • Is there a way to this not in amssymb? Because my work is on Wordpress, and I either use their built-in Latex or mathurl.com, neither of which support amssymb I am sure. Sorry to trouble you.
    – j4fj49
    Commented Apr 8, 2012 at 12:23
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    In trying this, I see that it requires displaymath mode; using inline $...$ puts the super/subscripts after the operator. What is the reason for this; I thought displaymath mode just affected the spacing around the maths? Commented Mar 4, 2013 at 11:58
  • 1
    Using \stackrel instead does allow it to be used within inline maths, but obviously that won't allow the arrow, superscript and subscript (since \stackrel only supports a top and a bottom). Commented Mar 4, 2013 at 12:21
10

I found a simple solution that works for me:

A \overset{F}{\underset{G}\rightleftarrows} X 
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  • Works well with the js parsers too! Commented Aug 27, 2018 at 9:59
6

If you want an extensible arrow, you can use the trick found in Herber Voß's Mathmode (texdoc mathmode or http://texdoc.net/pkg/mathmode):

\documentclass{article}
\usepackage{amsmath}
\makeatletter
\newcommand\xleftrightarrow[2][]{\ext@arrow 0099{\longleftrightarrowfill@}{#1}{#2}}
\def\longleftrightarrowfill@{\arrowfill@\leftarrow\relbar\rightarrow}
\makeatother
\begin{document}
$a\xleftrightarrow[under]{over}b$
\end{document}

enter image description here

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  • I added a link to texdoc.net because I didn't seem to be able to get Mathmode on my MiKTeX 2.9, hope that's alright.
    – doncherry
    Commented Apr 8, 2012 at 13:10
  • And congratulations to your answer No. 2000! I'll be lucky if I can keep my own rep to about a tenth of yours :)
    – doncherry
    Commented Apr 8, 2012 at 14:31
1

I experienced a similar problem and wasn't getting a satisfying answer. The problem is that the length of the arrows should "grow" with the text, or, at least, it should be possible to set the length manually. Finally, I found a solution for the last option (the first one not yet solved).

\stackrel[\mathrm{discharge}]{\mathrm{charge}}{\overrightarrow{\underleftarrow{\hspace{2cm}}}}

The 2 cm can be changed as needed, the word above the arrow are "charge" and below "discharge"

-2

You can also consider using \stackrel

\stackrel{\rm{1:1}}{\rightarrow}

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