# Get a black \mathring symbol

How can I get a black \mathring circle above variable, same as \mathring except the circle is "filled"?

-
possible duplicate of How to put a big dot (and circle) over a variable? –  Caramdir May 17 '11 at 5:29
@Caradir: the bullet as accent is too big! –  dearmath May 19 '11 at 3:19

Only the Latin Modern fonts allow for fonts smaller than 5pt (other scalable font families should not need the change of family)

\usepackage{accents}
\newcommand{\sbullet}{%
\hbox{\fontfamily{lmr}\fontsize{4}{0}\selectfont\textbullet}}

$\mathring{W}\accentset{\sbullet}{W}$


A more general definition might be

\usepackage{accents}
\makeatletter
\newcommand{\sbullet}{%
\hbox{\fontfamily{lmr}\fontsize{.4\dimexpr(\f@size pt)}{0}\selectfont\textbullet}}
\DeclareRobustCommand{\mathbullet}{\accentset{\sbullet}}
\makeatother


-
\documentclass{article}
\usepackage{amsmath}
\begin{document}
$\overset{\bullet}{x}\quad\mathring{x}$
\end{document}


The placement is clearly not very satisfied compared to \mathring. But I think is the a solution with minimal dependence on availability of fonts. Better solutions will depend on font packages specific commands.

-

Would \dot{x} do?

doesn't need any packages as fat as I know.

-