% \iffalse meta-comment
%
% Copyright (C) 2002-2007 by Morten Hoegholm <mh.ctan@gmail.com>
%
% 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 Morten Hoegholm.
%
% This work consists of the main source file empheq07.dtx
% and the derived files
%    empheq07.sty, empheq07.pdf, empheq07.ins, empheq07.drv.
%
% Distribution:
%    CTAN:macros/latex/contrib/mh/empheq07.dtx
%    CTAN:macros/latex/contrib/mh/empheq07.pdf
%
% Unpacking:
%    (a) If empheq07.ins is present:
%           tex empheq07.ins
%    (b) Without empheq07.ins:
%           tex empheq07.dtx
%    (c) If you insist on using LaTeX
%           latex \let\install=y\input{empheq07.dtx}
%        (quote the arguments according to the demands of your shell)
%
% Documentation:
%    (a) If empheq07.drv is present:
%           latex empheq07.drv
%    (b) Without empheq07.drv:
%           latex empheq07.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 empheq07.dtx
%       makeindex -s gind.ist empheq07.idx
%       pdflatex empheq07.dtx
%       makeindex -s gind.ist empheq07.idx
%       pdflatex empheq07.dtx
%
% Installation:
%    TDS:tex/latex/mh/empheq07.sty
%    TDS:doc/latex/mh/empheq07.pdf
%    TDS:source/latex/mh/empheq07.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: empheq07 2007/12/03 v0.7e empheq07 (MH)}
\Msg{************************************************************************}

\keepsilent
\askforoverwritefalse

\preamble

This is a generated file.

Copyright (C) 2002-2007 by Morten Hoegholm <mh.ctan@gmail.com>

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 Morten Hoegholm.

This work consists of the main source file empheq07.dtx
and the derived files
   empheq07.sty, empheq07.pdf, empheq07.ins, empheq07.drv.

\endpreamble

\generate{%
  \file{empheq07.ins}{\from{empheq07.dtx}{install}}%
  \file{empheq07.drv}{\from{empheq07.dtx}{driver}}%
  \usedir{tex/latex/mh}%
  \file{empheq07.sty}{\from{empheq07.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{*     empheq07.sty}
\Msg{*}
\Msg{* To produce the documentation run the file `empheq07.drv'}
\Msg{* through LaTeX.}
\Msg{*}
\Msg{* Happy TeXing!}
\Msg{*}
\Msg{************************************************************************}

\endbatchfile
%</install>
%<*ignore>
\fi
%</ignore>
%<*driver>
\NeedsTeXFormat{LaTeX2e}
\ProvidesFile{empheq07.drv}%
  [2007/12/03 v0.7e Emphasizing equations (MH)]
\documentclass{ltxdoc}
\usepackage{empheq07}
\usepackage{color,fancybox,ifpdf}
\ifpdf\else
  \usepackage{pstricks}
\fi
\definecolor{lightblue}{rgb}{.8, .8, 1}
\OnlyDescription
\begin{document}
\DocInput{empheq07.dtx}
\end{document}
%</driver>
% \fi
% \DeclareRobustCommand{\mode}[1]{\texttt{#1}}
% \DeclareRobustCommand{\env}[1]{\textsf{#1}}
% \DeclareRobustCommand{\pkg}[1]{\texttt{#1}}
% \DeclareRobustCommand{\EQ}{\pkg{empheq07}}
%
%  \changes{v0.7d}{2004/07/27}{Changed name to \pkg{empheq07} by request
%  of Robin Fairbairns}
%
%  \changes{v0.7c}{2004/04/01}{Separated \pkg{empheq} and
%  \pkg{empheq-obsolete}}
%
%  \changes{v0.7b}{2004/03/13}{Upgraded license to LPPL version 1.3.
%  The package is still obsolete}
%
%  \changes{v0.7a}{2004/02/15}{This package is now obsolete and has
%  changed its name to \pkg{empheq-obsolete}}
%
% \changes{v0.6a}{2003/01/28}{Minor updates to documentation.}
%
% \changes{v0.5}{2002/12/30}{First experimental and very limited release}
% \newif\ifBonusExample
% \ifpdf\else
% \BonusExampletrue
% \fi
% \GetFileInfo{empheq07.drv}
% \CheckSum{1273}
% \title{The \EQ\ package\thanks{This file
%        has version number \fileversion, last
%        revised \filedate.}\\Emphasizing equations in \LaTeXe
% \thanks{Thanks to Lars Madsen for asking for the subtle feature
% that evolved into this package.}}
% \author{Morten H\o gholm}
% \date{\filedate}
%
% \maketitle
%
%
% \begin{abstract}
% \noindent The \EQ\ package automatically detects several \pkg{amsmath}
% environments and the size of the displayed math material. The user
% interface makes it easy to add various kinds of visual markup to
% these equations.
% \end{abstract}
% \tableofcontents
%  \section{Important Notice}
%
%  This package (\EQ\ \fileversion) is no longer supported. See the
%  documentation of \pkg{empheq} for more details.
%
%
% \section{Introduction}
% Users who have wanted to put a system of equations inside boxes has
% hitherto been forced to use the features of \pkg{fancybox} or the \cmd{\boxed} command
% of \pkg{amsmath}. Both alternatives have serious limitations though.
% \pkg{fancybox} allows only \env{eqnarray}-style equations and at
% the end of the day they aren't all that pretty. Most mathematical
% typesetting in \LaTeX\ is done with the aid of \pkg{amsmath}
% anyway, but it only offers the single line quick-fix \cmd{\boxed}.
% What we really want is something that will enable us to do
% something along the likes of this:
% \begin{subequations}\label{eq:1}
% \begin{empheq}[boxtype=\fbox,Left= {\tilde{S}=1 \Rightarrow\empheqlbrace}]
% \begin{align}
% a&=\int_{-2}^3{t}b^t \, dt \quad\text{and} \label{eq:1a}\\
% c&=d-a \label{eq:1b}
% \end{align}
% \end{empheq}
% \end{subequations}
% As you can see, \EQ\ can do all the tricks the \pkg{cases} package
% by Donald Arseneau can do and more. It even supports
% \env{subequations}---as shown in equations \eqref{eq:1a} and
% \eqref{eq:1b}---from \pkg{amsmath} without complaining.
%
% In order to combine the best of two worlds the \EQ\ package
% tries to take advantage of the widespread features of \pkg{amsmath}.
% As it should be well known if you read this, \pkg{amsmath} has
% amongst its arsenal of structures \env{align}, \env{gather}, \env{alignat} and \env{multline}.
% \EQ\ works with these as well as their starred
% variants.
%
% ``But what about \env{equation}?'' you say.  \env{equation} is (in
% my opinion) merely a poor man's \env{gather}. If you really want
% to use \EQ's features on a one-liner (no pun intended) go with
% \env{gather}. Anyway the real goal of this package is to do nifty
% tricks with multi line equations \ldots
%
%
% \section{Examples}
% \changes{v0.7}{2003/05/11}{Added further examples and changed existing ones}
% Any options given to \EQ\ is passed on to \pkg{amsmath}, thus the
% line\par
% \cmd{\usepackage}\oarg{options}|{empheq07}|\\
% will load \pkg{amsmath} with exactly those options. \EQ\ doesn't
% redefine anything so to use it in an existing document you need
% only replace \pkg{amsmath} with \EQ---no harm done.
%
%
% \EQ\ is \emph{really} easy to use; you simply put an \env{empheq}
% environment around your \pkg{amsmath} environment:
% \begin{verbatim}
% \begin{empheq}
%   \begin{align}
%     E&=mc^2 \\
%     Y&= \sum_{n=1}^\infty \frac{1}{n^2}
%   \end{align}
% \end{empheq}
% \end{verbatim}
% \begin{empheq}
%   \begin{align}
%     E&=mc^2 \\
%     Y&= \sum_{n=1}^\infty \frac{1}{n^2}
%   \end{align}
% \end{empheq}
% Impressed? No? Well then I guess it's about time I told you about
% the \emph{optional} argument of the \env{empheq} environment. It allows
% you control what material to put on either side of the math and
% the sort of box to go around it all. That means that we can say
% \begin{verbatim}
% \begin{empheq}[boxtype=\fbox]
%   \begin{align}
%     E&=mc^2 \\
%     Y&= \sum_{n=1}^\infty \frac{1}{n^2}
%   \end{align}
% \end{empheq}
% \end{verbatim}
% to obtain the display
% \begin{empheq}[boxtype=\fbox]
%   \begin{align}
%     E&=mc^2 \\
%     Y&= \sum_{n=1}^\infty \frac{1}{n^2}
%   \end{align}
% \end{empheq}
% This requires the use of the \pkg{keyval} package from the tools
% bundle, which is undoubtedly installed on your system. When using
% the \pkg{keyval} package there are a few things we need to keep in
% mind. In mathematical typesetting `|=|' and `|,|' are quite
% frequently used, thus requiring the user to enclose them in
% braces:
% \begin{verbatim}
% \begin{empheq}[boxtype=\fbox,
%                Left={(a,b)=(c,i) \Rightarrow\empheqlbrace}]
% \begin{alignat}{2}
% (a,b)&= (\cos^a c, \tan^b i)&& \quad\text{for $i>1$}\\
% (a,b)&= (\arccos x^a, \arctan i^b)&& \quad\text{for $i\leq1$}
% \end{alignat}
% \end{empheq}
% \end{verbatim}
% \begin{empheq}[boxtype=\fbox,
%                Left={(a,b)=(c,i) \Rightarrow\empheqlbrace}]
% \begin{alignat}{2}
% (a,b)&= (\cos^a c, \tan^b i)&& \quad\text{for $i>1$}\\
% (a,b)&= (\arccos c^a, \arctan i^b)&& \quad\text{for $i\leq1$}
% \end{alignat}
% \end{empheq}
% The same with \env{cases} from \pkg{amsmath} for comparison:
% \[
% \boxed{(a,b)=(c,i) \Rightarrow
% \begin{cases} (a,b)= (\cos^a c, \tan^b i)& \text{for $i>1$}\\
% (a,b)= (\arccos x^a, \arctan i^b)& \text{for $i\leq1$}
% \end{cases}}
% \]
% Notice that \env{cases} uses an array for the conditions, so you
% have to force \cmd{\displaystyle} yourself. This is not needed with
% \EQ\ as you're already using a \cmd{\displaystyle} environment such as
% \env{gather} etc.
%
% \changes{v0.6b}{2003/03/04}{Added example for changing margins inside the boxtype.}
% Observe what can be done if we replace
% |\fbox| with another framed box and add some space on all sides:
% \begin{verbatim}
% \definecolor{lightblue}{rgb}{.8, .8, 1}
% \begin{empheq}[boxtype={\setlength{\fboxsep}{10pt}%
%                         \colorbox{lightblue}},
%                Right={\empheqrbrace \beta}]
%      .
%      .
%      .
% \end{empheq}
% \end{verbatim}
% \begin{empheq}[boxtype={\setlength{\fboxsep}{10pt}%
%                         \colorbox{lightblue}},Right={\empheqrbrace \beta}]
% \begin{align}
% a&=\int_{-2}^3{t}b^t \, dt \quad\text{and}\\
% c&=d-a
% \end{align}
% \end{empheq}
%
% As a convenience for the user, it is also possible to declare
% delimiters with the commands
% \cmd{\DeclareRightDelimiter}\marg{delimiter} and its companion
% \cmd{\DeclareLeftDelimiter}\marg{delimiter}. For instance the commands
%  \begin{quote}
% |\DeclareRightDelimiter{\rangle}| defines  \cmd{\empheqrangle}
%  \end{quote}
%  and
%  \begin{quote}
%  |\DeclareLeftDelimiter{\langle}| defines \cmd{\empheqlangle}.
%  \end{quote}
% The usage is simple.  \DeclareRightDelimiter{\rangle} \DeclareLeftDelimiter{\langle}
% \begin{verbatim}
% \begin{empheq}[Right=\empheqrangle,
%                Left=\empheqlangle]
%  \begin{gather}
%    a=b \\
%    c=d
%  \end{gather}
% \end{empheq}
% \end{verbatim}
% \begin{empheq}[Right=\empheqrangle,Left=\empheqlangle]
%  \begin{gather}
%    a=b \\
%    c=d
%  \end{gather}
% \end{empheq}
% \cmd{\DeclareRightDelimiter} and its companion have an optional
% argument which controls spacing (default is a negative thinspace),
% but beware: It will simply overwrite the original definition and
% it might not look all that pretty as the following example shows:
% \DeclareRightDelimiter[\>]{\rangle}
% \DeclareLeftDelimiter[\mkern-10mu]{\langle}
% \begin{verbatim}
% \DeclareRightDelimiter[\>]{\rangle}
% \DeclareLeftDelimiter[\mkern-10mu]{\langle}
% \end{verbatim}
% \begin{empheq}[Right=\empheqrangle,Left=\empheqlangle]
%  \begin{gather}
%    a=b \\
%    c=d
%  \end{gather}
% \end{empheq}
%
% These examples will have given you a glimpse of the possibilities
% \EQ\ offers. In particular the commands \cmd{\empheqlbrace} and
% \cmd{\empheqrbrace} produce braces just tall enough to encompass
% the display. You can of course use \cmd{\big...} delimiters if you
% want.
%
% \ifBonusExample
% If you want you can even create your own box and use it with
% \env{empheq}. In the following silly example I have created
% \cmd{\ErrorBox} with \pkg{PSTricks} to achieve a disturbing
% effect:
% \makeatletter
% \newcommand{\ErrorBox}[1]{%
%    \setlength{\@tempdima}{\heightof{#1}}%
%    \addtolength{\@tempdima}{\depthof{#1}}%
%    \setlength{\@tempdimb}{\widthof{#1}}%
%    \psset{yunit=\@tempdima}%
%    \psset{xunit=\@tempdimb}%
%    \psframebox[fillstyle=vlines,linestyle=none,hatchsep=.2\@tempdimb,hatchcolor=red,hatchangle=-60]{%
%    \rlap{\kern.5\@tempdimb\makebox[0pt]{{\Large\color{gray} \textbf{Error!}}}}#1}%
% }
% \makeatother
% \begin{empheq}[boxtype=\ErrorBox]
% \begin{align*}
%  E&=mc^3 \\
%  F&=G\frac{m+M}{r^2}
% \end{align*}
% \end{empheq}
% Remember one thing when creating your own box: Make it
% symmetrical.
% \fi
%
% \section{Bugs and shortcomings}
%  This package (\EQ) is not supported anymore. Try with the new
%  version and see if it works; if not, then contact me. See how in
%  the manual of \pkg{empheq}.
%
% \StopEventually{}
% \section{Implementation}
% \subsection{Strategy}
%
% Whenever \pkg{amsmath} is typesetting a display environment it
% actually does it twice; the first for the ``measuring'' phase and
% the second for the ``production'' phase. The \EQ\ package uses a
% similar approach:
%  \begin{itemize}
%     \item Collects the input in a token register for later use.
%     \item Typesets the input in the background and checks certain values to determine the kind of math structure you just typed.
%     \item Based on the given information, alterations are made to various lengths.
%     \item Then the equations are typeset again and stored in a box
%     for easy retrieval.
%     \item Finally the saved box is put into a box of the user's liking.
%     Any material to the right or left of the math structure (added with
%     the |Left| and |Right| keys) are put into the box as well.
%  \end{itemize}
%  Assuming we have found out which \pkg{amsmath} structure the
% user typed, there are still a few things we need to sort out
% before we proceed.
%
% First of all the equation number should still be aligned with
% those of the ordinary math structures, which is a problem as soon
% as the additions we make to the left and the right
% differ---presumably they will. And when we are in \mode{fleqn}
% mode, we should make sure that the structure is shifted just
% enough to the right so that all equations still are right
% adjusted. Therefore we need to make clever changes to the
% line width to make sure the margins come out right.
%
% Then assuming we have overcome all of this there's still the final
% step: Placing the math structure in the appropriate box at the
% appropriate position. Once again we need to do some manipulation
% with spacing to make it just right.
%
% \subsection{Preliminary actions}
%
% To avoid clashes with other packages, all private commands will contain the sequence \verb|@emphEQ@|.
%
% We will need \pkg{amsmath} of course and it would be nice if \EQ\
% would recognize all the \pkg{amsmath} options so we make that
% happen. To make sure the user has an updated system the newest
% release of \pkg{amsmath} is required.
%
% \pkg{calc} is used to increase readability of the code
% (thus making it \emph{far} easier to write too) and \pkg{keyval}
% is used for user friendliness. They should all be part of any
% \LaTeX\ system.
%    \begin{macrocode}
%<*package>
\ProvidesPackage{empheq07}%
  [2007/12/03 v0.7e Emphasizing equations (MH)]
\DeclareOption*{\PassOptionsToPackage{\CurrentOption}{amsmath}}
\ProcessOptions\relax
\RequirePackage{amsmath}[2000/07/18]
\RequirePackage{calc,keyval}
%    \end{macrocode}
% \begin{macro}{\if@emphEQ@FLL}\begin{macro}{\if@emphEQ@FLR}\begin{macro}{\if@emphEQ@L}\begin{macro}{\if@emphEQ@R}
%  There are four available layouts for mathematical displays:
% |[fleqn,leqno]| (FLL), |[fleqn,reqno]| (FLR), |[leqno]| (L) and |[reqno]| (R). We create four \TeX\ conditionals
%  to make the algorithm easier to read as well as to speed up things a bit.
%    \begin{macrocode}
\newif\if@emphEQ@FLL
\newif\if@emphEQ@FLR
\newif\if@emphEQ@L
\newif\if@emphEQ@R
%    \end{macrocode}
%\end{macro}\end{macro}\end{macro}\end{macro}
% We then perform a simple test to determine the current mode.
%    \begin{macrocode}
\if@fleqn
    \iftagsleft@
        \@emphEQ@FLLtrue
    \else
        \@emphEQ@FLRtrue
    \fi
\else
    \iftagsleft@
        \@emphEQ@Ltrue
    \else
        \@emphEQ@Rtrue
    \fi
\fi
%    \end{macrocode}
% \begin{macro}{\if@emphEQ@gather}\begin{macro}{\if@emphEQ@align}\begin{macro}{\if@emphEQ@alignat}
% \begin{macro}{\if@emphEQ@multline}\begin{macro}{\if@emphEQ@NoNumEq}
% Since we're going to determinate which math structure the user has
% input, we create some more conditionals to improve speed and
% readability. Furthermore it will show crucial to know whether or
% not the equation counter has been stepped since \env{multline$*$}
% and \env{multline} don't have exactly the same structure.
%    \begin{macrocode}
\newif\if@emphEQ@gather
\newif\if@emphEQ@align
\newif\if@emphEQ@alignat
\newif\if@emphEQ@multline
\newif\if@emphEQ@NoNumEq
%    \end{macrocode}
% \end{macro}\end{macro}\end{macro}\end{macro}\end{macro}
%
%
%
% \begin{macro}{\@emphEQ@Box}\begin{macro}{\@emphEQ@BoxWidth}
% \begin{macro}{\@emphEQ@displaywidth}\begin{macro}{\@emphEQ@mathbody}
% We need a single box to hold the math structure, a length so we
% can remember the size of the displayed math for later use and a
% token register for the math environment.
%    \begin{macrocode}
\newsavebox{\@emphEQ@Box}
\newlength{\@emphEQ@BoxWidth}
\newlength{\@emphEQ@displaywidth}
\newtoks\@emphEQ@mathbody
%    \end{macrocode}
% \end{macro}\end{macro}\end{macro}\end{macro}
% \begin{macro}{\@emphEQ@Left}\begin{macro}{\@emphEQ@Right}\begin{macro}{\@emphEQ@lwd}\begin{macro}{\@emphEQ@rwd}
% Here are some vital parts: The additional informations the user
% want to display on either side of the math structure are saved by
% \cmd{\@emphEQ@Left} and \cmd{\@emphEQ@Right} and \cmd{\@emphEQ@lwd} and \cmd{\@emphEQ@rwd}
% measure the width of them for later use.
%    \begin{macrocode}
\newcommand{\@emphEQ@Left}{}
\newcommand{\@emphEQ@Right}{}
\newlength{\@emphEQ@lwd}
\newlength{\@emphEQ@rwd}
%    \end{macrocode}
% \end{macro}\end{macro}\end{macro}\end{macro}
% \begin{macro}{\@emphEQ@boxtype}\begin{macro}{\@emphEQ@boxtypelength}
% \begin{macro}{\@emphEQ@shadowbox}\begin{macro}{\if@emphEQ@shadowbox}
% To make sure spacing is right when putting the math structure into
% a box, we need to know what kind of box it is: The width is
% extremely important. Often we will have to subtract or add half of
% an empty (but \emph{not} zero-width) box' width to certain
% lengths. When using an \cmd{\fbox} or \cmd{\colorbox} this is just
% \cmd{\fboxrule}+\cmd{\fboxsep}, but when using say,
% \cmd{\doublebox} of \pkg{fancybox} fame the necessity arises.
% \pkg{fancybox} also defines \cmd{\shadowbox} which needs extra
% taking care of, since it's asymmetrical unlike most other framed
% boxes.
%
% Thus we test whether or not \pkg{fancybox} has been loaded at the
% beginning of the document. If it has, we don't lift a finger; if
% it hasn't, we let \cmd{\fbox} be an alias for \cmd{\shadowbox}.
% Then we create a private version of \cmd{\shadowbox} for
% testing purposes and a conditional for the algorithm.
%    \begin{macrocode}
\newcommand{\@emphEQ@boxtype}{}
\newlength{\@emphEQ@boxtypelength}
\AtBeginDocument{%
    \@ifpackageloaded{fancybox}{}{%
        \let\shadowbox=\fbox}}
\newcommand{\@emphEQ@shadowbox}{\shadowbox}
\newif\if@emphEQ@shadowbox
%    \end{macrocode}
% \end{macro}\end{macro}\end{macro}\end{macro}
% \begin{macro}{\@emphEQ@templength}\begin{macro}{@emphEQ@EqCtr}
% We are almost ready to go. We only need two temporary little
% helpers: one length and one counter.
%    \begin{macrocode}
\newlength{\@emphEQ@templength}
\newcounter{@emphEQ@EqCtr}
%    \end{macrocode}
% \end{macro}\end{macro}
%
% \subsubsection{Faraway, so close}\label{sec:CloseEnough}
% \begin{macro}{\@emphEQ@CloseEnough}
% \changes{v0.6}{2003/01/10}{Added a test for lengths being almost identical}
% When determining the display type we will occasionally have to check if an equation of the
% form
%  \[
%  \cmd{\totwidth@}-\cmd{\tagshift@}=\cmd{\linewidth}
%  \]
% is true. However small rounding errors \emph{can} occur in
% \env{alignat} so we would rather see if the equation
%  \[
%  -\delta<\cmd{\totwidth@}-\cmd{\tagshift@}-\cmd{\linewidth}<\delta
%  \]
% holds for some sufficiently small $\delta>\text{$0$ pt}$. I have used $\delta=\text{$5$ sp}$.
%    \begin{macrocode}
\newcommand{\@emphEQ@CloseEnough}[4]{%
    \setlength{\@tempdima}{#1-#2}%
    \ifdim\@tempdima>-5sp
        \ifdim\@tempdima<5sp
            #3
        \else
            #4
        \fi
    \else
        #4
    \fi
}
%    \end{macrocode}
%    \end{macro}
%
% \subsection{Saving the input}
% \begin{macro}{\@emphEQ@MainEnv}
% \changes{v0.7}{2003/05/11}{Added use of token register to remove the
% need for an extra \cmd{\write} and \pkg{verbatim}}
% \begin{macro}{\end@emphEQ@MainEnv}
% \begin{macro}{\@emphEQ@get@body}\begin{macro}{\@emphEQ@findend}
% \begin{macro}{\@emphEQ@EnvName}
% We start out by saving the input in the token register
% \cmd{\@emphEQ@mathbody}. The method is heavily inspired by
% \pkg{tabularx} \dots\@ No need to copy the words of David Carlisle here---his code will do!
%    \begin{macrocode}
\def\@emphEQ@MainEnv{%
    \edef\@emphEQ@EnvName{\@currenvir}%
    {\ifnum0=`}\fi
    \@emphEQ@mathbody{}\@emphEQ@get@body
}
\let\end@emphEQ@MainEnv\relax
\long\def\@emphEQ@get@body#1\end{%
    \@emphEQ@mathbody\expandafter{\the\@emphEQ@mathbody #1}%
    \@emphEQ@findend
}
\def\@emphEQ@findend#1{%
    \def\@tempa{#1}%
    \ifx\@tempa\@emphEQ@EnvName
        \expandafter\@emphEQ@PostProcess
    \else
        \@emphEQ@mathbody\expandafter{\the\@emphEQ@mathbody\end{#1}}%
        \expandafter\@emphEQ@get@body
    \fi
}
\def\@emphEQ@EnvName{@emphEQ@MainEnv}
%    \end{macrocode}
% \end{macro}\end{macro}\end{macro}\end{macro}\end{macro}
% \begin{macro}{@emphEQ@PostProcess}
% Now we can go on with the post processing, which is the real
% workhorse in this package.  The first job is to test if we're
% using a \cmd{\shadowbox} and then we set some \pkg{amsmath}
% dimensions to zero---\pkg{amsmath} doesn't do this by itself, and
% for that we can be thankful. Otherwise you wouldn't be reading
% this now~;-)
%    \begin{macrocode}
\newcommand*{\@emphEQ@PostProcess}{%
    \ifx\@emphEQ@boxtype\@emphEQ@shadowbox
        \@emphEQ@shadowboxtrue
    \else
        \@emphEQ@shadowboxfalse
    \fi
    \tagshift@=0pt \tagwidth@=0pt \totwidth@=0pt
    \eqnshift@=0pt \alignsep@=0pt
%    \end{macrocode}
% \subsection{The first pass}
% We then run the first pass to find out which environment we've
% got. However we have to store the equation counter because it is
% stepped in this pass, and we certainly don't want that to happen.
% As a side effect this will also tell us if the equations are
% numbered.
%
% If we are to put a brace to the left of the display, it would be
% rather pleasant to know just how high the structure is, since this
% will affect the height and more importantly the width the brace:
% we will need to know the \emph{exact} width of such material.
% Hence we put it in a box which is easy to measure and fiddle
% around with. To achieve this we put the contents of the token register
% \cmd{\@emphEQ@mathbody} in a \env{minipage} inside a \env{lrbox}. Alas,
% \env{lrbox} won't let us escape into display math mode, so we play
% a dirty trick on it and use a \env{minipage}, which will let us
% have our way with it.
%
% The \env{minipage} starts in horizontal mode and then goes
% straight to display math mode, thus adding some space before the
% display math. However there was nothing on the first line in the
% \env{minipage} thus leading \TeX\ to add a \cmd{\abovedisplayskip}
% before the display. We subtract this as fast as we can!
% Furthermore it showed in test runs, that an additional~1~pt had to
% be subtracted in the top---but not in the bottom. It has nothing
% to do with any of the standard page dimensions or parameters.
% Strange indeed.
%    \begin{macrocode}
    \setcounter{@emphEQ@EqCtr}{\value{equation}}%
    \begin{lrbox}{\@emphEQ@Box}%
        \begin{minipage}{\linewidth}%
        \vskip-\abovedisplayskip\relax\vskip-1pt\relax
        \the\@emphEQ@mathbody
        \end{minipage}%
    \end{lrbox}%
%    \end{macrocode}
% We then look at the equation counter to see if we had any numbered
% equations and reset it if that was the case. If we used a
% \env{multline$*$} we can detect this by measuring |\tagwidth@|.
%    \begin{macrocode}
    \ifnum\value{equation}=\value{@emphEQ@EqCtr}%
        \ifdim\tagwidth@>0pt
        \else
            \@emphEQ@NoNumEqtrue
        \fi
    \else
        \setcounter{equation}{\value{@emphEQ@EqCtr}}%
    \fi
%    \end{macrocode}
% Now we can determine the various math environments. Firstly we
% measure an empty \cmd{\@emphEQ@boxtype}---we will need this
% information when the math structure is finally put into a box of
% this type, but we have to take it into account when calculating
% the allowable width of \env{multline} displays because we want to
% use the margins already set for this environment.
%    \begin{macrocode}
    \settowidth{\@emphEQ@boxtypelength}{\@emphEQ@boxtype{}}%
%    \end{macrocode}
% The idea is that each of the \pkg{amsmath} multiple line
% environments can be singled out because it uses a certain
% dimension in a way none of the others use it.
% \begin{list}{}{}
%  \item[\env{align}:] Uses \cmd{\alignsep@} and sets it to something
%  positive. None of the others use it.
%  \item[\env{multline}:] Doesn't use \cmd{\eqnshift@}.
%  \item[\env{gather}:] Doesn't use \cmd{\tagshift@}.
%  \item[\env{alignat}:] Can be determined because some dimensions
%  will have special relations e.g., when in |[fleqn,reqno]| mode
%  the equation
%  \[
%  \cmd{\totwidth@}-\cmd{\tagshift@}=\cmd{\linewidth}
%  \]
%  holds\footnote{Well almost---they may be off by a few scaled points.
%  See section~\ref{sec:CloseEnough} for further details.}
%  and similarly for the other three display modes. See the
%  code for these equations.
% \end{list}
%
% \subsubsection{\mode{[fleqn,leqno]}}
% ~
%    \begin{macrocode}
    \if@emphEQ@FLL % fleqn and leqno
        \ifdim\alignsep@>0pt % => align
            \@emphEQ@aligntrue
            \setlength{\@emphEQ@displaywidth}{\tagshift@-\@mathmargin}%
        \else
            \ifdim\eqnshift@=0pt % => multline %tagwidth@>
                \@emphEQ@multlinetrue
                \if@emphEQ@NoNumEq
                    \setlength{\@emphEQ@displaywidth}{%
                        \linewidth-\multlinegap-\@mathmargin
                        -\@emphEQ@boxtypelength}%
                \else
                    \setlength{\@emphEQ@displaywidth}{%
                        \linewidth-\tagwidth@-\multlinegap
                        -\multlinetaggap-\@emphEQ@boxtypelength}%
                \fi
            \else
                \ifdim\tagshift@=0pt % => gather
                    \@emphEQ@gathertrue
                    \setlength{\@emphEQ@displaywidth}{%
                        \totwidth@-\@mathmargin}%
                \else
                    \ifdim\tagshift@=\totwidth@ % => alignat
                        \@emphEQ@alignattrue
                        \setlength{\@emphEQ@displaywidth}{%
                            \totwidth@-\@mathmargin}%
                    \else
                        %Nothing thus far...
                    \fi
                \fi
            \fi
        \fi
    \fi
%    \end{macrocode}
% \subsubsection{\mode{[fleqn,reqno]}}
% ~
%    \begin{macrocode}
    \if@emphEQ@FLR % fleqn and reqno
        \ifdim\alignsep@>0pt % => align
            \@emphEQ@aligntrue
            \setlength{\@emphEQ@displaywidth}{%
                \linewidth-\@mathmargin+\tagshift@}%
        \else
            \ifdim\eqnshift@=0pt % => multline
                \@emphEQ@multlinetrue
                \if@emphEQ@NoNumEq
                    \setlength{\@emphEQ@displaywidth}{%
                        \linewidth-\multlinegap-\@mathmargin
                        -\@emphEQ@boxtypelength}%
                \else
                    \setlength{\@emphEQ@displaywidth}{%
                        \linewidth-\tagwidth@-\@mathmargin
                        -\multlinetaggap-\@emphEQ@boxtypelength}%
                \fi
            \else
                \ifdim\tagshift@=0pt % => gather
                    \@emphEQ@gathertrue
                    \setlength{\@emphEQ@displaywidth}{%
                        \totwidth@-\@mathmargin}%
                \else
                    \@emphEQ@CloseEnough{\totwidth@-\tagshift@}%
                    {\linewidth}%
                    {\@emphEQ@alignattrue
                    \setlength{\@emphEQ@displaywidth}%
                    {\totwidth@-\eqnshift@}}{}%
                \fi
            \fi
        \fi
    \fi
%    \end{macrocode}
% \subsubsection{\mode{[reqno]}}
% ~
%    \begin{macrocode}
    \if@emphEQ@R % reqno
        \ifdim\alignsep@>0pt % => align
            \@emphEQ@aligntrue
            \setlength{\@emphEQ@displaywidth}{\totwidth@}%
        \else
            \ifdim\eqnshift@=0pt % => multline
                \@emphEQ@multlinetrue
                \if@emphEQ@NoNumEq
                    \setlength{\@emphEQ@displaywidth}{%
                        \linewidth-2\multlinegap
                        -\@emphEQ@boxtypelength}%
                \else
                    \setlength{\@emphEQ@displaywidth}{%
                        \linewidth-\tagwidth@-\multlinegap
                        -\multlinetaggap-\@emphEQ@boxtypelength}%
                \fi
            \else
                \ifdim\tagshift@=0pt % => gather
                    \@emphEQ@gathertrue
                    \setlength{\@emphEQ@displaywidth}{\totwidth@}%
                \else
                    \@emphEQ@CloseEnough{\tagshift@}{-\eqnshift@}%
                    {\@emphEQ@alignattrue
                    \setlength{\@emphEQ@displaywidth}{\totwidth@}}{}%
                \fi
            \fi
        \fi
    \fi
%    \end{macrocode}
% \subsubsection{\mode{[leqno]}}
% ~
%    \begin{macrocode}
    \if@emphEQ@L % leqno
        \ifdim\alignsep@>0pt % => align
            \@emphEQ@aligntrue
            \setlength{\@emphEQ@displaywidth}{\totwidth@}%
        \else
            \ifdim\eqnshift@=0pt % => multline
                \@emphEQ@multlinetrue
                \if@emphEQ@NoNumEq
                    \setlength{\@emphEQ@displaywidth}{%
                        \linewidth-2\multlinegap
                        -\@emphEQ@boxtypelength}%
                \else
                    \setlength{\@emphEQ@displaywidth}{%
                        \linewidth-\tagwidth@-\multlinegap
                        -\multlinetaggap-\@emphEQ@boxtypelength}%
                \fi
            \else
                \ifdim\tagshift@=0pt % => gather
                    \@emphEQ@gathertrue
                    \setlength{\@emphEQ@displaywidth}{\totwidth@}%
                \else
                    \@emphEQ@CloseEnough{%
                        \linewidth-\eqnshift@}{\tagshift@}{%
                        \@emphEQ@alignattrue
                        \setlength{\@emphEQ@displaywidth}{\totwidth@}}%
                        {}%
                \fi
            \fi
        \fi
    \fi
%    \end{macrocode}
% Phew! That was tedious, but necessary. I wish I could say it got
% better further down the road, but it doesn't. Now we can measure
% the width of the additional material on both sides of the math
% structure. We add braces here and there to avoid any
% \cmd{\thinmuskip}'s.
%    \begin{macrocode}
    \settowidth{\@emphEQ@lwd}{${\@emphEQ@Left}%
                               {\vphantom{\usebox{\@emphEQ@Box}}}$}%
    \settowidth{\@emphEQ@rwd}{${\vphantom{\usebox{\@emphEQ@Box}}}%
                               {\@emphEQ@Right}$}%
%    \end{macrocode}
%
% \subsection{The second pass}
%
% When we try to create an effect as in the preliminary example
% there are a few things we need to tell \LaTeX\ for the overall
% result to be acceptable. If the display math is centered, then the
% new one should also be centered. This means that when typesetting
% the math structure for the second time, we need to make
% adjustments to \cmd{\linewidth}, \cmd{\@mathmargin} etc.\ for the
% equation tag to be placed correctly.
%
% That process is extremely tedious, but there are only few
% shortcuts, so we just go through each of the four environments, check
% each of the four display modes and alter dimensions a we trudge
% along. First we check if we are trying to put something into an
% asymmetrical box and then make it symmetrical be removing the size
% of the shadow.
%    \begin{macrocode}
    \begin{lrbox}{\@emphEQ@Box}%
    \if@emphEQ@shadowbox
        \addtolength{\@emphEQ@boxtypelength}{-\shadowsize}%
    \fi
%    \end{macrocode}
% \subsubsection{\env{align}}
% ~
%    \begin{macrocode}
    \if@emphEQ@align
        \if@emphEQ@FLL
            \begin{minipage}{\linewidth+\@emphEQ@lwd
                +.5\@emphEQ@boxtypelength}%
                \addtolength{\@mathmargin}{\@emphEQ@lwd
                    +.5\@emphEQ@boxtypelength}%%
        \fi
        \if@emphEQ@FLR
            \begin{minipage}{\linewidth}%
                \addtolength{\@mathmargin}{\@emphEQ@lwd
                    +.5\@emphEQ@boxtypelength}%%
        \fi
        \if@emphEQ@L
            \begin{minipage}{\linewidth+\@emphEQ@lwd-\@emphEQ@rwd}%
        \fi
        \if@emphEQ@R
            \begin{minipage}{\linewidth-\@emphEQ@lwd+\@emphEQ@rwd}%
        \fi
    \fi
%    \end{macrocode}
% \subsubsection{\env{gather}}
% ~
%    \begin{macrocode}
    \if@emphEQ@gather
        \if@emphEQ@FLL
            \begin{minipage}{\linewidth+\@emphEQ@lwd
                +.5\@emphEQ@boxtypelength}%
                \addtolength{\@mathmargin}{\@emphEQ@lwd
                    +.5\@emphEQ@boxtypelength}%%
        \fi
        \if@emphEQ@FLR
            \begin{minipage}{\linewidth}%
                \addtolength{\@mathmargin}{\@emphEQ@lwd
                    +.5\@emphEQ@boxtypelength}%%
        \fi
        \if@emphEQ@R
            \setlength{\@emphEQ@templength}{\linewidth-\totwidth@
                       -\eqnshift@}%
            \begin{minipage}{\linewidth-\@emphEQ@lwd+\@emphEQ@rwd
                             +\@emphEQ@templength-\eqnshift@}%
        \fi
        \if@emphEQ@L
            \setlength{\@emphEQ@templength}{\linewidth-\totwidth@
                       -\eqnshift@}%
            \begin{minipage}{\linewidth+\@emphEQ@lwd-\@emphEQ@rwd
                             -\@emphEQ@templength+\eqnshift@}%
        \fi
    \fi
%    \end{macrocode}
% \subsubsection{\env{alignat}}
% ~
%    \begin{macrocode}
    \if@emphEQ@alignat
        \if@emphEQ@FLL
            \begin{minipage}{\linewidth+\@emphEQ@lwd
                +.5\@emphEQ@boxtypelength}%
                \addtolength{\@mathmargin}{\@emphEQ@lwd
                    +.5\@emphEQ@boxtypelength}%%
        \fi
        \if@emphEQ@FLR
            \begin{minipage}{\linewidth}%
                \addtolength{\@mathmargin}{\@emphEQ@lwd
                    +.5\@emphEQ@boxtypelength}%%
        \fi
        \if@emphEQ@L
            \begin{minipage}{\linewidth+\@emphEQ@lwd-\@emphEQ@rwd}%
        \fi
        \if@emphEQ@R
            \begin{minipage}{\linewidth-\@emphEQ@lwd+\@emphEQ@rwd}%
        \fi
    \fi
%    \end{macrocode}
% \subsubsection{\env{multline}}
% ~
%    \begin{macrocode}
    \if@emphEQ@multline
        \if@emphEQ@FLL
            \begin{minipage}{\linewidth}%
                \if@emphEQ@NoNumEq
                    \addtolength{\@mathmargin}{\@emphEQ@lwd
                        +.5\@emphEQ@boxtypelength}%
                    \if@emphEQ@shadowbox
                        \addtolength{\@mathmargin}{\shadowsize}
                    \fi%
                \else
                    \addtolength{\multlinetaggap}{\@emphEQ@lwd
                        +.5\@emphEQ@boxtypelength}%
                    \if@emphEQ@shadowbox
                        \addtolength{\multlinegap}{\shadowsize}%
                    \fi
                \fi
                \addtolength{\multlinegap}{\@emphEQ@rwd
                    +.5\@emphEQ@boxtypelength}%
        \fi
        \if@emphEQ@FLR
            \begin{minipage}{\linewidth}%
                \if@emphEQ@NoNumEq
                    \addtolength{\multlinegap}{\@emphEQ@rwd
                        +.5\@emphEQ@boxtypelength}%
                    \if@emphEQ@shadowbox
                        \addtolength{\multlinegap}{\shadowsize}%
                    \fi
                \else
                    \addtolength{\multlinetaggap}{\@emphEQ@rwd
                        +.5\@emphEQ@boxtypelength}%
                    \if@emphEQ@shadowbox
                        \addtolength{\multlinetaggap}{\shadowsize}%
                    \fi
                \fi
                \addtolength{\@mathmargin}{\@emphEQ@lwd
                    +.5\@emphEQ@boxtypelength}%
        \fi
        \if@emphEQ@L
            \begin{minipage}{\linewidth}%
                \if@emphEQ@NoNumEq
                    \addtolength{\multlinegap}{.5\@emphEQ@rwd
                        +.5\@emphEQ@lwd+.5\@emphEQ@boxtypelength}%
                    \if@emphEQ@shadowbox
                        \addtolength{\multlinegap}{.5\shadowsize}%
                    \fi
                \else
                    \addtolength{\multlinetaggap}{\@emphEQ@lwd
                        +.5\@emphEQ@boxtypelength}%
                    \addtolength{\multlinegap}{\@emphEQ@rwd
                        +.5\@emphEQ@boxtypelength}%
                    \if@emphEQ@shadowbox
                        \addtolength{\multlinegap}{\shadowsize}%
                    \fi
                \fi
        \fi
        \if@emphEQ@R
            \begin{minipage}{\linewidth}%
                \if@emphEQ@NoNumEq
                    \addtolength{\multlinegap}{.5\@emphEQ@rwd
                        +.5\@emphEQ@lwd+.5\@emphEQ@boxtypelength}%
                    \if@emphEQ@shadowbox
                        \addtolength{\multlinegap}{.5\shadowsize}
                    \fi
                \else
                    \addtolength{\multlinetaggap}{\@emphEQ@rwd
                        +.5\@emphEQ@boxtypelength}%
                    \addtolength{\multlinegap}{\@emphEQ@lwd
                        +.5\@emphEQ@boxtypelength}%
                    \if@emphEQ@shadowbox
                        \addtolength{\multlinetaggap}{\shadowsize}
                    \fi
                \fi
        \fi
    \fi
%    \end{macrocode}
% Finally we get to typeset the contents of \cmd{\@emphEQ@mathbody} for
% the second time\ldots
%    \begin{macrocode}
    \vskip-\abovedisplayskip\relax\vskip-1pt\relax
    \the\@emphEQ@mathbody
    \end{minipage}%
    \end{lrbox}%
%    \end{macrocode}
%
% \subsection{Putting it into the box}
%
% Because we were clever to start with---by measuring the width of
% the display math  and storing it in
% \cmd{\@emphEQ@displaywidth}---we can now put it into a box of
% width
% \cmd{\@emphEQ@displaywidth}+\cmd{\@emphEQ@rwd}+\cmd{\@emphEQ@lwd}.
% This doesn't apply to \env{multline} though: it has to be set in a
% box of width \cmd{\@emphEQ@displaywidth}.
%    \begin{macrocode}
\setlength{\@emphEQ@BoxWidth}{\@emphEQ@displaywidth+\@emphEQ@rwd
                              +\@emphEQ@lwd}%
%    \end{macrocode}
% \subsubsection{\env{align}}
% ~
%    \begin{macrocode}
\if@emphEQ@align
    \if@emphEQ@FLL
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@BoxWidth][l]{%
            \if@emphEQ@shadowbox \kern.5\shadowsize \fi
            $\@emphEQ@Left$%
            \kern-.5\@emphEQ@boxtypelength%
            \kern-\@mathmargin
            \kern-\@emphEQ@lwd
            \usebox{\@emphEQ@Box}%
            \kern-\@emphEQ@displaywidth
            \kern-\@emphEQ@rwd
            \kern-\@emphEQ@lwd
            $\@emphEQ@Right$}}%
    \fi
    \if@emphEQ@FLR
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@BoxWidth][l]{%
            \if@emphEQ@shadowbox \kern.5\shadowsize \fi
            $\@emphEQ@Left$%
            \kern-.5\@emphEQ@boxtypelength%
            \kern-\@mathmargin
            \kern-\@emphEQ@lwd
            \usebox{\@emphEQ@Box}%
            \kern-\alignsep@
            $\@emphEQ@Right$}}%
    \fi
    \if@emphEQ@L
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@BoxWidth][c]{%
            %\kern\eqnshift@
            %\kern-\alignsep@
            $\@emphEQ@Left$%
            \kern-\eqnshift@
            %\kern-\alignsep@
            \usebox{\@emphEQ@Box}%
            %\kern-\eqnshift@
            \kern-\alignsep@
            $\@emphEQ@Right$}}%
    \fi
    \if@emphEQ@R
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@BoxWidth][c]{%
            $\@emphEQ@Left$%
            \kern-\eqnshift@
            \usebox{\@emphEQ@Box}%
            \kern-\eqnshift@
            $\@emphEQ@Right$}}%
    \fi
\fi
%    \end{macrocode}
% \subsubsection{\env{alignat}}
% ~
%    \begin{macrocode}
\if@emphEQ@alignat
    \if@emphEQ@FLL
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@BoxWidth][l]{%
            \if@emphEQ@shadowbox \kern.5\shadowsize \fi
            $\@emphEQ@Left$%
            \kern-.5\@emphEQ@boxtypelength
            \kern-\@mathmargin
            \kern-\@emphEQ@lwd
            \usebox{\@emphEQ@Box}%
            \kern\@mathmargin
            \kern\@emphEQ@displaywidth
            \kern-\linewidth
            $\@emphEQ@Right$}}%
    \fi
    \if@emphEQ@FLR
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@BoxWidth][l]{%
            \if@emphEQ@shadowbox \kern.5\shadowsize \fi
            $\@emphEQ@Left$%
            \kern-.5\@emphEQ@boxtypelength
            \kern-\@mathmargin
            \kern-\@emphEQ@lwd
            \usebox{\@emphEQ@Box}%
            \kern\@mathmargin
            \kern\@emphEQ@displaywidth
            \kern-\linewidth
            \kern\@emphEQ@lwd
            \kern.5\@emphEQ@boxtypelength
            $\@emphEQ@Right$}}%
    \fi
    \if@emphEQ@L
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@BoxWidth][c]{%
            $\@emphEQ@Left$%
            \kern-\eqnshift@
            \usebox{\@emphEQ@Box}%
            \kern-\eqnshift@
            $\@emphEQ@Right$}}%
    \fi
    \if@emphEQ@R
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@BoxWidth][c]{%
            $\@emphEQ@Left$%
            \kern-\eqnshift@
            \usebox{\@emphEQ@Box}%
            \kern-\eqnshift@
            $\@emphEQ@Right$}}%
    \fi
\fi
%    \end{macrocode}
% \subsubsection{\env{gather}}
% ~
%    \begin{macrocode}
\if@emphEQ@gather
    \if@emphEQ@FLL
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@BoxWidth][l]{%
            \if@emphEQ@shadowbox \kern.5\shadowsize \fi
            $\@emphEQ@Left$%
            \kern-.5\@emphEQ@boxtypelength
            \kern-\@mathmargin
            \kern-\@emphEQ@lwd
            \usebox{\@emphEQ@Box}%
            \kern-\linewidth
            \kern\@mathmargin
            \kern\@emphEQ@displaywidth
            $\@emphEQ@Right$}}%
    \fi
    \if@emphEQ@FLR
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@BoxWidth][l]{%
            \if@emphEQ@shadowbox \kern.5\shadowsize
            \fi
            $\@emphEQ@Left$%
            \kern-.5\@emphEQ@boxtypelength
            \kern-\@mathmargin
            \kern-\@emphEQ@lwd
            \usebox{\@emphEQ@Box}%
            \kern-\linewidth
            \kern.5\@emphEQ@boxtypelength
            \kern\@mathmargin
            \kern\@emphEQ@displaywidth
            \kern\@emphEQ@lwd
            $\@emphEQ@Right$}}%
    \fi
    \if@emphEQ@L
        \setlength{\tagwidth@}{\eqnshift@+\@emphEQ@rwd}%
        \setlength{\@emphEQ@templength}{\linewidth-\totwidth@
                                        -\eqnshift@}%
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@BoxWidth][c]{%
            \ifdim\@emphEQ@templength<\tagwidth@
                \setlength{\tagwidth@}{\@emphEQ@templength
                                       +\@emphEQ@lwd}%
                \ifdim\tagwidth@<\eqnshift@
                    \kern-\@emphEQ@templength
                    \kern\eqnshift@
                \fi
            \else
                \kern-\@emphEQ@lwd
                \kern\@emphEQ@rwd
                \kern-\@emphEQ@templength
                \kern\eqnshift@
            \fi
            $\@emphEQ@Left$%
            \kern-\eqnshift@
            \usebox{\@emphEQ@Box}%
            %\kern-\eqnshift@
            \kern-\@emphEQ@lwd
            \kern\@emphEQ@rwd
            \kern-\@emphEQ@templength
            $\@emphEQ@Right$}}%
    \fi
    \if@emphEQ@R
        \setlength{\tagwidth@}{\eqnshift@+\@emphEQ@rwd}%
        \setlength{\@emphEQ@templength}{\linewidth-\totwidth@
                                        -\eqnshift@}%
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@BoxWidth][c]{%
            \kern-\@emphEQ@lwd
            \kern\@emphEQ@rwd
            \kern\@emphEQ@templength
            \kern-\eqnshift@
            $\@emphEQ@Left$%
            \ifdim\@emphEQ@templength>\tagwidth@
                \kern-\eqnshift@
            \else
                \kern\@emphEQ@lwd
                \kern-\@emphEQ@rwd
                \kern-\@emphEQ@templength
            \fi
            \usebox{\@emphEQ@Box}%
            \kern-\eqnshift@
            $\@emphEQ@Right$}}%
    \fi
\fi
%    \end{macrocode}
% \subsubsection{\env{multline}}
%
% \env{multline} is somewhat more difficult because \env{multline$*$}
% differs on several accounts. Thus we make use of our little test
% to see if the math structure was numbered to begin with
% (\verb|\if@emphEQ@NoNumEq|).
%    \begin{macrocode}
\if@emphEQ@multline
    \if@emphEQ@FLL
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@displaywidth][l]{%
            \if@emphEQ@shadowbox \kern.5\shadowsize \fi
            $\@emphEQ@Left$%
            \kern-.5\@emphEQ@boxtypelength
            \kern-\@emphEQ@lwd
            \if@emphEQ@NoNumEq
                \if@emphEQ@shadowbox \kern-\shadowsize \fi
                \kern-\@mathmargin
            \else
                \kern-\tagwidth@
                \kern-\multlinetaggap
            \fi
            \usebox{\@emphEQ@Box}%
            \kern-\@emphEQ@boxtypelength
            \if@emphEQ@NoNumEq
                \kern-\multlinegap
            \else
                \kern\multlinegap
            \fi
            \kern-\@emphEQ@rwd
            \kern-\@emphEQ@lwd
            \kern-\@mathmargin
            $\@emphEQ@Right$}}%
    \fi
    \if@emphEQ@FLR
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@displaywidth][l]{%
            \if@emphEQ@shadowbox \kern.5\shadowsize \fi
            $\@emphEQ@Left$%
            \kern-.5\@emphEQ@boxtypelength
            \kern-\@emphEQ@lwd
            \kern-\@mathmargin
            \usebox{\@emphEQ@Box}%
            \kern-\@emphEQ@boxtypelength
            \kern-\@emphEQ@rwd
            \kern-\@emphEQ@lwd
            \if@emphEQ@NoNumEq
                \kern-\multlinegap
            \else
                \kern-\multlinetaggap
            \fi
            \kern-\@mathmargin
            \kern-\tagwidth@
            $\@emphEQ@Right$}}%
    \fi
    \if@emphEQ@L
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@displaywidth][l]{%
            \if@emphEQ@shadowbox \kern.5\shadowsize \fi
            $\@emphEQ@Left$%
            \kern-.5\@emphEQ@boxtypelength
            \kern-\@emphEQ@lwd
            \if@emphEQ@NoNumEq
                \kern-\multlinegap
                \kern.5\@emphEQ@lwd
                \kern-.5\@emphEQ@rwd
                \if@emphEQ@shadowbox \kern-.5\shadowsize \fi
            \else
                \kern-\multlinetaggap
                \kern-\tagwidth@
            \fi
            \usebox{\@emphEQ@Box}%
            \kern-.5\@emphEQ@boxtypelength
            \if@emphEQ@NoNumEq
                \kern.5\@emphEQ@rwd
                \kern-.5\@emphEQ@lwd
            \fi
            \kern-\@emphEQ@rwd
            \kern-\multlinegap
            $\@emphEQ@Right$}}%
    \fi
    \if@emphEQ@R
        \savebox{\@emphEQ@Box}{\makebox[\@emphEQ@displaywidth][l]{%
            \if@emphEQ@shadowbox \kern.5\shadowsize \fi
            $\@emphEQ@Left$%
            \kern-.5\@emphEQ@boxtypelength
            \if@emphEQ@NoNumEq
                \if@emphEQ@shadowbox \kern-.5\shadowsize \fi
                \kern-.5\@emphEQ@rwd
                \kern.5\@emphEQ@lwd
            \fi
            \kern-\@emphEQ@lwd
            \kern-\multlinegap
            \usebox{\@emphEQ@Box}%
            \kern-.5\@emphEQ@boxtypelength
            \kern-\@emphEQ@rwd
            \if@emphEQ@NoNumEq
                \kern-\multlinegap
                \kern-.5\@emphEQ@lwd
                \kern.5\@emphEQ@rwd
            \else
                \kern-\multlinetaggap
            \fi
            \kern-\tagwidth@
            $\@emphEQ@Right$}}%
    \fi
\fi
%    \end{macrocode}
%
% \subsubsection{The final step}
%
% At last here comes the good part! We are now ready to place the
% box containing all of our math material. If we have used a
% \env{multline} we have to do a few kerning tricks but at least we
% would seem to know the drill by now\ldots To make sure vertical
% spacing is ok, we put it all into a simple math environment
% \verb|\[...\]|.
%    \begin{macrocode}
\[
    \if@emphEQ@align
        \if@emphEQ@L
            \kern-\alignsep@
            \kern\eqnshift@
        \fi
    \fi
    \if@emphEQ@gather
        \if@emphEQ@L
            \kern-\@emphEQ@templength
            \kern\eqnshift@
            \kern\@emphEQ@rwd
            \kern-\@emphEQ@lwd
        \fi
        \if@emphEQ@R
            \setlength{\tagwidth@}{\eqnshift@+\@emphEQ@rwd}%
            \ifdim\@emphEQ@templength>\tagwidth@
                \kern-\@emphEQ@templength
                \kern\eqnshift@
                \kern\@emphEQ@lwd
            \else
                \kern\@emphEQ@templength
                \kern-\eqnshift@
                \kern\@emphEQ@rwd
                \kern-\@emphEQ@lwd
            \fi
        \fi
    \fi
    \if@emphEQ@multline
        \if@emphEQ@NoNumEq
            % naught
        \else
            \if@emphEQ@FLL
                \kern-\@mathmargin
                \kern\tagwidth@
                \kern\multlinetaggap
            \fi
            \if@emphEQ@L
                \kern\tagwidth@
                \kern\multlinetaggap
                \kern-\multlinegap
            \fi
            \if@emphEQ@R
                \kern-\tagwidth@
                \kern-\multlinetaggap
                \kern\multlinegap
            \fi
        \fi
    \else
%    \end{macrocode}
% If we are using a \cmd{\shadowbox} in centered display mode, I
% would rather that the shadowsize is ignored when placing the box.
% Reason: I think it looks better. Judge for yourself:
% \begin{gather}
% a=b\\
% \Phi(x)=\int_{-\infty}^x e^{-t^2/2}\, dt
% \end{gather}
%
% \begin{empheq}[boxtype=\shadowbox]
% \begin{gather}
% a=b\\
% \Phi(x)=\int_{-\infty}^x e^{-t^2/2}\, dt
% \end{gather}
% \end{empheq}
%    \begin{macrocode}
        \if@emphEQ@shadowbox
            \if@emphEQ@R
                \kern\shadowsize
            \fi
            \if@emphEQ@L
                \kern\shadowsize
            \fi
        \fi
    \fi
        \@emphEQ@boxtype{\usebox{\@emphEQ@Box}}%
%    \end{macrocode}
% After all is done, we empty out the added material and the
% boxtype.
%    \begin{macrocode}
        \gdef\@emphEQ@Left{}\gdef\@emphEQ@Right{}%
        \gdef\@emphEQ@boxtype{}%
    \]%
    \ifnum0=`{\fi}%
    \expandafter\end\expandafter{\@emphEQ@EnvName}%
}
%    \end{macrocode}
%
% \subsection{Going public\ldots}
% \begin{macro}{boxtype}\begin{macro}{Left}\begin{macro}{Right}\begin{macro}{empheq}
% In order to simplify the user interface, we make use of
% \pkg{keyval}. We define three keys to be used along with a more
% accessible version of \env{@emphEQ@MainEnv}.
% \changes{v0.7}{2003/05/11}{Changed the user interface slightly}
%    \begin{macrocode}
\define@key{empheq}{boxtype}{\renewcommand\@emphEQ@boxtype{#1}}
\define@key{empheq}{Left}{\def\@emphEQ@Left{#1}}
\define@key{empheq}{Right}{\def\@emphEQ@Right{#1}}
\newenvironment{empheq}[1][]{\setkeys{empheq}{#1}\@emphEQ@MainEnv}%
                          {\end@emphEQ@MainEnv\ignorespacesafterend}%
%    \end{macrocode}
% \end{macro}\end{macro}\end{macro}\end{macro}
% \begin{macro}{\DeclareLeftDelimiter}
% \changes{v0.7}{2003/05/11}{Added delimiter interface}
% \begin{macro}{\DeclareRightDelimiter}
% \changes{v0.7}{2003/05/11}{Added delimiter interface}
% It might come in handy to have delimiters of the appropriate size
% available to cover the math display as in \eqref{eq:1}. Therefore
% we define two commands that will create such delimiters once and
% for all.
% Use this as an inspiration for further kinds of delimiters.
%    \begin{macrocode}
\newcommand{\DeclareLeftDelimiter}[2][\!]{%
    \@namedef{empheq\expandafter\@gobble\string#2}{
    \left#2
    \vphantom{\usebox{\@emphEQ@Box}}%
    \right.#1}}
\newcommand{\DeclareRightDelimiter}[2][\!]{%
    \@namedef{empheq\expandafter\@gobble\string#2}{%
        #1\left.
        \vphantom{\usebox{\@emphEQ@Box}}%
        \right#2}}%
\DeclareRightDelimiter{\rbrace}
\DeclareLeftDelimiter{\lbrace}
%</package>
%    \end{macrocode}
% \end{macro}\end{macro}\end{macro}
% \Finale
\endinput
