# Add a comment on top of “equal” and “approximate” symbols [duplicate]

I was wondering whether it is possible to add some comment on top of the \approx symbol in a similar way that the command \xrightarrow{text} produces an arrow with text over it.

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–  Andrew Swann Mar 15 at 10:42

## marked as duplicate by mafp, lockstep, Claudio Fiandrino, Werner, Martin SchröderMar 15 at 15:50

You can use the \stackrel{}{} for this:

\documentclass[preview]{standalone}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\newcommand{\approxtext}[1]{\ensuremath{\stackrel{\text{#1}}{\approx}}}
\begin{document}
$\displaystyle A \stackrel{\text{text}}{\approx} B$,
$\displaystyle A \approxtext{test} B$
\end{document}


Or a small wrapper: \newcommand{\approxtext}[1]{\ensuremath{\stackrel{\text{#1}}{\approx}}}. Result:

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The text above the symbol should probably treated as text, not as math. What's the purpose of the additional braces? –  egreg Mar 15 at 10:33
Thanks for such a detailed explanation However, I don't see the difference between the different approaches? I found that I can also accommodate math in the text above by the usual prescription $mathtext$ –  pablo Mar 15 at 10:54

You can use \stackrel{a=b}{\approx} or if it is real text \stackrel{\text{your text}}{\approx} if your text is not too long. The \approx symbol is rather small, so I wouldn't add too much on top to keep your equations readable.

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That's working perfect! Thanks for the quickness! Just to know, which package does it comes from this? ams math? –  pablo Mar 15 at 10:53
@pablo: Actually, you don't even need amsmath for this. But amsmath has two more commands: \overset and \underset. The former does basically the same as \stackrel –  Anke Mar 15 at 11:13
As already mentioned \stackrel can be used for it. I'd just recommend adding \scriptscriptstyle or, say, \tiny if it is just text, plus \smash. Otherwise one often ends up having a combined symbol that mess with the line spacing if used in the text.
\newcommand\defeq{\stackrel{\smash{\scriptscriptstyle\mathrm{def}}}{=}}

\smash to remove the height completely (the small size then help us not to overlap too much with the line above)