# DeclareMathOperator and fontawesome: Spacing problems

I am trying to use the symbol \faPlus from the latex package fontawesome and I have some troubles with the spacing.

I declare my symbol with \DeclareMathOperator\plus{\text{\rm\scriptsize\faPlus}} The \text is there because it is not a math command. The \rm is there because there is no "italics" version, and so to avoid problems, the size is just a choice otherwise it is too big.

My problem is that the spacing looks not well. For example, if I put $\star\plus\star$ I get this:

But if I write $(\star)\plus(\star)$ or \langle\star\rangle\plus\langle\star\rangle I get this:

where the symbol is clearly not centered.

Here is the full example:

\documentclass{article}

\usepackage{amsmath}     % for \DeclareMathOperator macro
\usepackage{fontawesome} % for the \faPlus symbol

\DeclareMathOperator{\plus}{\textrm{\rm\scriptsize\faPlus}}

\begin{document}
$\star\plus\star$
$(\star)\plus(\star)$
$\langle\star\rangle\plus\langle\star\rangle$
\end{document}


You want to use \mathbin, not the \mathop that's used by \DeclareMathOperator, which is for operators such as “sin” or “log”, not for binary operation symbols.

\documentclass{article}

\usepackage{amsmath}     % for math
\usepackage{fontawesome} % for the \faPlus symbol

\newcommand{\plus}{\mathbin{\textnormal{\scriptsize\faPlus}}}

\begin{document}
$\star\plus\star$
$(\star)\plus(\star)$
$\langle\star\rangle\plus\langle\star\rangle$
\end{document}


Please, note that \rm has been deprecated for 30 years.

I'd probably use \scalebox, though, so the symbol also properly scales in subscripts, and add a small space on either side, because the symbol \faPlus has a very tight bounding box.

\documentclass{article}

\usepackage{amsmath}     % for \DeclareMathOperator macro
\usepackage{fontawesome} % for the \faPlus symbol
\usepackage{graphicx}    % for \scalebox

\newcommand{\plus}{\mathbin{\mspace{1mu}\text{\scalebox{0.7}{\faPlus}}\mspace{1mu}}}

\begin{document}

$\star\plus\star_{a\plus b}$
$(\star)\plus(\star)$
$\langle\star\rangle\plus\langle\star\rangle$
\end{document}


• Excellent! Thanks. I noticed that the problem had nothing to do with the symbol, and I edited the question to make it more general. Your answer is perfect. Thanks. Dec 15, 2021 at 22:38
• @AlejandroDC Please, roll back, possibly also adding the more general question. There are specific parts for the usage of fontawesome in this context, which are addressed to in the answer. Dec 15, 2021 at 22:45
• Rolled back. Thanks. Dec 15, 2021 at 23:24