Double harpoons?

[db]

I want to write a reversible chemial reaction using
what I call double harpoons, but they don't seem to
exist in LaTeX. Or do they? Using \longdoublearrows
doesn't quite make it.

[Athel Cornish-Bowden]

Post by db
I want to write a reversible chemial reaction using
what I call double harpoons, but they don't seem to
exist in LaTeX. Or do they? Using \longdoublearrows
doesn't quite make it.

I have felt the same need and the same frustration at not finding a
good solution.

What I do is

\newcommand {\reversible}{\hspace*{-0.08cm}\begin{array}{c}
_\rightarrow\\[-0.17cm]
^\leftarrow\\
\end{array}\hspace*{-0.08cm}}

This does what I want, but not necessarily what you want.

[Ulrike Fischer]

Post by db
I want to write a reversible chemial reaction using
what I call double harpoons, but they don't seem to
exist in LaTeX. Or do they? Using \longdoublearrows
doesn't quite make it.

\documentclass{article}
\usepackage{chemformula}
\begin{document}
$\rightleftharpoons$

\ch{N<>N} \ch{N<=>N} \ch{N>=<N} \ch{N<=>>N}

\end{document}

[Dr Engelbert Buxbaum]

In article <vbehvm$p6bk$***@dont-email.me>, ***@gmail.com
says...

Post by db
I want to write a reversible chemial reaction using
what I call double harpoons, but they don't seem to
exist in LaTeX. Or do they? Using \longdoublearrows
doesn't quite make it.

You can use the chemarrow package, it provides (amongst others) the
\rightleftharpoons and \autorightleftharpoons{}{} commands. In the
latter command, the length of the harpoons is adjusted to the text above
and below them.