% \iffalse meta-comment
%
% Copyright (C) 2006 by Heiko Oberdiek <oberdiek@uni-freiburg.de>
%
% This work may be distributed and/or modified under the
% conditions of the LaTeX Project Public License, either
% version 1.3 of this license or (at your option) any later
% version. The latest version of this license is in
%    http://www.latex-project.org/lppl.txt
% and version 1.3 or later is part of all distributions of
% LaTeX version 2005/12/01 or later.
%
% This work has the LPPL maintenance status "maintained".
%
% This Current Maintainer of this work is Heiko Oberdiek.
%
% This work consists of the main source file centernot.dtx
% and the derived files
%    centernot.sty, centernot.pdf, centernot.ins, centernot.drv.
%
% Distribution:
%    CTAN:macros/latex/contrib/oberdiek/centernot.dtx
%    CTAN:macros/latex/contrib/oberdiek/centernot.pdf
%
% Unpacking:
%    (a) If centernot.ins is present:
%           tex centernot.ins
%    (b) Without centernot.ins:
%           tex centernot.dtx
%    (c) If you insist on using LaTeX
%           latex \let\install=y\input{centernot.dtx}
%        (quote the arguments according to the demands of your shell)
%
% Documentation:
%    (a) If centernot.drv is present:
%           latex centernot.drv
%    (b) Without centernot.drv:
%           latex centernot.dtx; ...
%    The class ltxdoc loads the configuration file ltxdoc.cfg
%    if available. Here you can specify further options, e.g.
%    use A4 as paper format:
%       \PassOptionsToClass{a4paper}{article}
%
%    Programm calls to get the documentation (example):
%       pdflatex centernot.dtx
%       makeindex -s gind.ist centernot.idx
%       pdflatex centernot.dtx
%       makeindex -s gind.ist centernot.idx
%       pdflatex centernot.dtx
%
% Installation:
%    TDS:tex/latex/oberdiek/centernot.sty
%    TDS:doc/latex/oberdiek/centernot.pdf
%    TDS:source/latex/oberdiek/centernot.dtx
%
%<*ignore>
\begingroup
  \def\x{LaTeX2e}
\expandafter\endgroup
\ifcase 0\ifx\install y1\fi\expandafter
         \ifx\csname processbatchFile\endcsname\relax\else1\fi
         \ifx\fmtname\x\else 1\fi\relax
\else\csname fi\endcsname
%</ignore>
%<*install>
\input docstrip.tex
\Msg{************************************************************************}
\Msg{* Installation}
\Msg{* Package: centernot 2006/12/02 v1.0 Centers the not symbol horizontally (HO)}
\Msg{************************************************************************}

\keepsilent
\askforoverwritefalse

\preamble

This is a generated file.

Copyright (C) 2006 by Heiko Oberdiek <oberdiek@uni-freiburg.de>

This work may be distributed and/or modified under the
conditions of the LaTeX Project Public License, either
version 1.3 of this license or (at your option) any later
version. The latest version of this license is in
   http://www.latex-project.org/lppl.txt
and version 1.3 or later is part of all distributions of
LaTeX version 2005/12/01 or later.

This work has the LPPL maintenance status "maintained".

This Current Maintainer of this work is Heiko Oberdiek.

This work consists of the main source file centernot.dtx
and the derived files
   centernot.sty, centernot.pdf, centernot.ins, centernot.drv.

\endpreamble

\generate{%
  \file{centernot.ins}{\from{centernot.dtx}{install}}%
  \file{centernot.drv}{\from{centernot.dtx}{driver}}%
  \usedir{tex/latex/oberdiek}%
  \file{centernot.sty}{\from{centernot.dtx}{package}}%
}

\obeyspaces
\Msg{************************************************************************}
\Msg{*}
\Msg{* To finish the installation you have to move the following}
\Msg{* file into a directory searched by TeX:}
\Msg{*}
\Msg{*     centernot.sty}
\Msg{*}
\Msg{* To produce the documentation run the file `centernot.drv'}
\Msg{* through LaTeX.}
\Msg{*}
\Msg{* Happy TeXing!}
\Msg{*}
\Msg{************************************************************************}

\endbatchfile
%</install>
%<*ignore>
\fi
%</ignore>
%<*driver>
\NeedsTeXFormat{LaTeX2e}
\ProvidesFile{centernot.drv}%
  [2006/12/02 v1.0 Centers the not symbol horizontally (HO)]
\documentclass{ltxdoc}
\usepackage{holtxdoc}
\usepackage{centernot}
\begin{document}
  \DocInput{centernot.dtx}
\end{document}
%</driver>
% \fi
%
% \CheckSum{23}
%
% \CharacterTable
%  {Upper-case    \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
%   Lower-case    \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
%   Digits        \0\1\2\3\4\5\6\7\8\9
%   Exclamation   \!     Double quote  \"     Hash (number) \#
%   Dollar        \$     Percent       \%     Ampersand     \&
%   Acute accent  \'     Left paren    \(     Right paren   \)
%   Asterisk      \*     Plus          \+     Comma         \,
%   Minus         \-     Point         \.     Solidus       \/
%   Colon         \:     Semicolon     \;     Less than     \<
%   Equals        \=     Greater than  \>     Question mark \?
%   Commercial at \@     Left bracket  \[     Backslash     \\
%   Right bracket \]     Circumflex    \^     Underscore    \_
%   Grave accent  \`     Left brace    \{     Vertical bar  \|
%   Right brace   \}     Tilde         \~}
%
% \GetFileInfo{centernot.drv}
%
% \title{The \xpackage{centernot} package}
% \date{2006/12/02 v1.0}
% \author{Heiko Oberdiek\\\xemail{oberdiek@uni-freiburg.de}}
%
% \maketitle
%
% \begin{abstract}
% This package provides \cs{centernot} that prints the symbol
% \cs{not} on the following argument. Unlike \cs{not} the symbol
% is horizontally centered.
% \end{abstract}
%
% \tableofcontents
%
% \section{User interface}
%
% If a negotiated relational symbol is not available, \cs{not}
% can be used to create the negotiated variant of the relational
% symbol. The disadvantage of \cs{not} is that it is put at
% a fixed location regardless of the width of the relational
% symbol. Therefore \cs{centernot} takes an argument and
% measures its width to achieve a better placement of the
% symbol \cs{not}.
% Examples:
% \begin{quote}
%   \begin{tabular}{@{}cccl@{}}
%     Symbol & \cs{not} & \cs{centernot} &\\
%     \hline
%     |=| & $\not=$ & $\centernot=$ & \textit{(definition)}\\
%     \cs{parallel} & $\not\parallel$ & $\centernot\parallel$\\
%     \cs{longrightarrow} &
%       $\not\longrightarrow$ & $\centernot\longrightarrow$
%   \end{tabular}
% \end{quote}
%
% \StopEventually{
% }
%
% \section{Implementation}
%
%    \begin{macrocode}
%<*package>
\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{centernot}
  [2006/12/02 v1.0 Centers the not symbol horizontally (HO)]
%    \end{macrocode}
%
%    \noindent
%    \cs{not} is a \cs{mathrel} atom with zero width. It prints itself
%    outside its character box, similar to \cs{rlap}. The next
%    \cs{mathrel} symbol is then print on top of it. \TeX\ does not
%    add space between two \cs{mathrel} atoms. The following implementation
%    assumes that the math font is designed in such a way that the
%    position of \cs{not} fits well on the equal symbol.
%
%    The blue boxes marks the character bounding boxes seen by \TeX:
%    \begin{quote}
%      \setlength{\fboxrule}{.8pt}
%      \setlength{\fboxsep}{.8pt}
%      \def\xbox#1{^^A
%        \begingroup
%          \large
%          \color{blue}%
%          \fbox{\color{black}\boldmath$#1$}^^A
%          \kern-2\fboxsep
%          \kern-2\fboxrule
%        \endgroup
%      }
%      \begin{tabular}{@{}c@{\qquad}c@{\qquad}c@{}}
%        |\not| & |=| & |\not=|\\
%        \xbox{\not} & \xbox{=} & \xbox{\not}\xbox{=}
%      \end{tabular}
%    \end{quote}
%    \begin{macro}{\centernot}
%    \cs{centernot} is not a symbol but a macro that takes
%    one argument. It measures the width of the argument
%    and places \cs{not} horizontally centered on that argument.
%    The result is a \cs{mathrel} atom.
%    \begin{macrocode}
\newcommand*{\centernot}{%
  \mathpalette\@centernot
}
\def\@centernot#1#2{%
  \mathrel{%
    \rlap{%
      \settowidth\dimen@{$\m@th#1{#2}$}%
      \kern.5\dimen@
      \settowidth\dimen@{$\m@th#1=$}%
      \kern-.5\dimen@
      $\m@th#1\not$%
    }%
    {#2}%
  }%
}
\makeatother
%    \end{macrocode}
%    \end{macro}
%
%    \begin{macrocode}
%</package>
%    \end{macrocode}
% \section{Installation}
%
% \paragraph{CTAN.} This package is available on
% CTAN\footnote{\url{ftp://ftp.ctan.org/tex-archive/}}:
% \begin{description}
% \item[\CTAN{macros/latex/contrib/oberdiek/centernot.dtx}] The source file.
% \item[\CTAN{macros/latex/contrib/oberdiek/centernot.pdf}] Documentation.
% \end{description}
%
% \paragraph{Unpacking.} The \xfile{.dtx} file is a self-extracting
% \docstrip\ archive. The files are extracted by running the
% \xfile{.dtx} through \plainTeX:
% \begin{quote}
%   \verb|tex centernot.dtx|
% \end{quote}
%
% \paragraph{TDS.} Now the different files must be moved into
% the different directories in your installation TDS tree
% (also known as \xfile{texmf} tree):
% \begin{quote}
% \sbox0{^^A
% \begin{tabular}{@{}>{\ttfamily}l@{$\quad\rightarrow\quad$}>{\ttfamily}l@{}}
%   centernot.sty & tex/latex/oberdiek/centernot.sty\\
%   centernot.pdf & doc/latex/oberdiek/centernot.pdf\\
%   centernot.dtx & source/latex/oberdiek/centernot.dtx\\
% \end{tabular}^^A
% }%
% \ifdim\wd0>\linewidth
%   \mbox{}\nobreak\hskip0pt minus\leftmargin
%   \usebox0
%   \nobreak\hskip0pt minus\rightmargin
% \else
%   \usebox0
% \fi
% \end{quote}
% If you have a \xfile{docstrip.cfg} that configures and enables \docstrip's
% TDS installing feature, then some files can already be in the right
% place, see the documentation of \docstrip.
%
% \paragraph{Refresh file databases.} If your \TeX~distribution
% (\teTeX, \mikTeX, \dots) rely on file databases, you must refresh
% these. For example, \teTeX\ users run \verb|texhash| or
% \verb|mktexlsr|.
%
% \subsection{Some details for the interested}
%
% \paragraph{Attached source.}
%
% The PDF documentation on CTAN also includes the
% \xfile{.dtx} source file. It can be extracted by
% AcrobatReader 6 or higher. Another option is \textsf{pdftk},
% e.g. unpack the file into the current directory:
% \begin{quote}
%   \verb|pdftk centernot.pdf unpack_files output .|
% \end{quote}
%
% \paragraph{Unpacking with \LaTeX.}
% The \xfile{.dtx} chooses its action depending on the format:
% \begin{description}
% \item[\plainTeX:] Run \docstrip\ and extract the files.
% \item[\LaTeX:] Generate the documentation.
% \end{description}
% If you insist on using \LaTeX\ for \docstrip\ (really,
% \docstrip\ does not need \LaTeX), then inform the autodetect routine
% about your intention:
% \begin{quote}
%   \verb|latex \let\install=y\input{centernot.dtx}|
% \end{quote}
% Do not forget to quote the argument according to the demands
% of your shell.
%
% \paragraph{Generating the documentation.}
% You can use both the \xfile{.dtx} or the \xfile{.drv} to generate
% the documentation. The process can be configured by the
% configuration file \xfile{ltxdoc.cfg}. For instance, put this
% line into this file, if you want to have A4 as paper format:
% \begin{quote}
%   \verb|\PassOptionsToClass{a4paper}{article}|
% \end{quote}
% An example follows how to generate the
% documentation with pdf\LaTeX:
% \begin{quote}
%\begin{verbatim}
%pdflatex centernot.dtx
%makeindex -s gind.ist centernot.idx
%pdflatex centernot.dtx
%makeindex -s gind.ist centernot.idx
%pdflatex centernot.dtx
%\end{verbatim}
% \end{quote}
%
% \begin{History}
%   \begin{Version}{2006/12/02 v1.0}
%   \item
%     First version.
%   \end{Version}
% \end{History}
%
% \PrintIndex
%
% \Finale
\endinput
