\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{circle}[1998/07/15 LaTeX package for circles in math mode]
%\Author{Klaus G. Barthelmann, barthel@informatik.uni-mainz.de}
%\ProvidesCommands{\Circle[1][n]}

% As the name says, \Circle gives a circle in math mode. Its size lies between
% that of the binary operator \circ and that of the unary operator \bigcirc.
% It can be used as the nextstep operator of temporal logic in conjunction with
% \Box and \Diamond (latexsym) or \square and \lozenge (amssymb). \Circle[f]
% gives a filled circle.
% As you probably know, L. Lamport discouraged the use of the nextstep
% operator for program verification. This could be the reason that he did not
% provide a symbol for it in \LaTeX.
% The circles are taken from the lcircle10 font. We try to choose the
% appropriate size. If you need a high quality output, this solution will not
% suit you.

\newcommand*\Circle[1][n]{%
  \mathchoice{\@Circle{#1}{\tf@size}}{\@Circle{#1}{\tf@size}}%
             {\@Circle{#1}{\sf@size}}{\@Circle{#1}{\ssf@size}}%
}

% Bugs: circles have size n at fontsize 2n-1 and 2n; they do not scale linearly
%       depending on the fontsize

\newcommand*\@Circle[2]{{%
  \dimen0=#2pt \advance\dimen0by.5pt \dimen1=1pt \divide\dimen0by\dimen1
  \count255=\dimen0 \ifodd\count255 \advance\count255by1 \fi\divide\count255by2
  \ifnum\count255=0 {}\else\ifnum\count255>15 {}\else
    \dimen0=\count255pt
    \edef\circfont{tencirc\ifnum\count255>8 w\fi}
    \advance\count255by\if #1f111\else 95\fi
    \dimen2=.82\dimen0 \advance\dimen2by.4pt
    \raisebox{.625\dimen0}[\dimen2]{\makebox[1.2\dimen0]{%
      \hspace*{.9\dimen0}%
      \csname\circfont\endcsname
      \char\count255 %
    }}%
  \fi\fi
}}

\endinput