%%% ====================================================================
%%%  @LaTeX-style-file{
%%%     author          = "Braams J.L.",
%%%     version         = "2.0",
%%%     date            = "02 November 1993",
%%%     time            = "15:06:16 MET",
%%%     filename        = "subeqnarray.doc",
%%%     address         = "PTT Research
%%%                        St. Paulusstraat 4
%%%                        2264 XZ Leidschendam
%%%                        The Netherlands",
%%%     telephone       = "(70) 3325051",
%%%     FAX             = "(70) 3326477",
%%%     checksum        = "23077 186 688 7602",
%%%     email           = "J.L.Braams@research.ptt.nl (Internet)",
%%%     codetable       = "ISO/ASCII",
%%%     keywords        = "",
%%%     supported       = "yes",
%%%     abstract        = "This style option defines the subeqnarray
%%%                        and subeqnarray* environments, which behave
%%%                        like the eqnarray environment, except that
%%%                        the lines are numbered like 1a 1b 1c etc.
%%%                        To refer to these numbers an extra label
%%%                        command \slabel has been defined
%%%                        The equations and their numbers adhere to
%%%                        the standard LaTeX options leqno and fleqn.",
%%%     docstring       = "The checksum field above contains a CRC-16
%%%                        checksum as the first value, followed by the
%%%                        equivalent of the standard UNIX wc (word
%%%                        count) utility output of lines, words, and
%%%                        characters.  This is produced by Robert
%%%                        Solovay's checksum utility.",
%%%  }
%%% ====================================================================
%\iffalse
% Subeqnarray DOCUMENT-STYLE option -- Version 1.1 released 15 November 1988
%                                      Version 2.0 released  2 November 1993
%    for LaTeX version 2.09
% Copyright (C) 1988,1993 by Johannes Braams, Dr Neher Laboratories
%    This style option defines the subeqnarray and subeqnarray*
%    environment, which behaves like the eqnarray environment,
%    except that the lines are numbered like 1a 1b 1c etc.
%    To refer to these numbers an extra label command \slabel
%    has been defined.
%    Many of this code was taken from LaTeX.TeX and modified for
%    this purpose.
%\changes{22/12/88}{1.1}{Fixed bug in subeqnarray* environment}
%\makeshortverb`\|
%    \begin{macrocode}
\def\fileversion{2.0}
\def\filedate{02 November 1993}
\def\docdate{22/12/1988}
\wlog{Style option `subeqnarray' version \fileversion\space<\filedate> (JLB)}
\wlog{English documentation\space\space\space<\docdate> (JLB)}
%    \end{macrocode}
%    A new counter for the subequations
%    and a command to generate the number
%    \begin{macrocode}
\newcounter{subequation}[equation]
\def\thesubequation{\theequation\@alph\c@subequation}
%    \end{macrocode}
%  |\@subeqnnum=|: Produces the equation number for the
%     subeqnarray environment.  The following definition is for
%     flushright numbers; for flushleft numbers, see leqno.doc.
%     The {|\rm ...| } puts the subequation number in roman type even if
%     an subeqnarray environment appears in an italic environment.
%\changes{2.0}{2/11/93}{Added test for presence of the leqno option}
%    \begin{macrocode}
\ifx\ds@leqno\undefined
  \def\@subeqnnum{{\reset@font\rm (\thesubequation)}}
\else
  \def\@subeqnnum{\hbox to .01\p@{}\rlap{\reset@font\rm
        \hskip -\displaywidth(\thesubequation)}}
%    \end{macrocode}
%    A new label command to refer to subequations. It works
%    like the |\label| command and was taken from \LaTeX.TeX
%  |\slabel{FOO}| then writes the following on file |\@auxout| :
%        |\newlabel{FOO}{{eval(\@currentlabel)}{eval(\thepage)}}|
%    \begin{macrocode}
\def\slabel#1{\@bsphack\if@filesw {\let\thepage\relax
   \def\protect{\noexpand\noexpand\noexpand}%
   \edef\@tempa{\write\@auxout{\string
      \newlabel{#1}{{\thesubequation}{\thepage}}}}%
   \expandafter}\@tempa
   \if@nobreak \ifvmode\nobreak\fi\fi\fi\@esphack}
%    \end{macrocode}
%    Here's the subeqnarray environment,
%        it steps the equation counter,
%        sets the subequation counter equal to 1
%        and behaves much like the eqnarray environment.
%\changes{2.0}{2/11/93}{Added test for presence of fleqn style option}
%    \begin{macrocode}
\ifx\ds@fleqn\undefined
  \def\subeqnarray{%
    \stepcounter{equation}%
    \let\@currentlabel=\theequation
    \global\c@subequation\@ne
    \global\@eqnswtrue\m@th
    \global\@eqcnt\z@\tabskip\@centering\let\\\@subeqncr
    $$\m@th\halign to \displaywidth
     \bgroup\@eqnsel\hskip\@centering
      $\displaystyle\tabskip\z@{##}$%
      &\global\@eqcnt\@ne \hskip 2\arraycolsep \hfil${##}$\hfil
      &\global\@eqcnt\tw@ \hskip 2\arraycolsep
         $\displaystyle\tabskip\z@{##}$\hfil \tabskip\@centering
      &\llap{##}\tabskip\z@\cr}
\else
  \def\subeqnarray{%
    \stepcounter{equation}%
    \let\@currentlabel=\theequation
    \global\c@subequation\@ne
    \global\@eqnswtrue\m@th
    \global\@eqcnt\z@\tabskip\mathindent\let\\\@subeqncr
    \abovedisplayskip\topsep
    \ifvmode\advance\abovedisplayskip\partopsep\fi
    \belowdisplayskip\abovedisplayskip
    \belowdisplayshortskip\abovedisplayskip
    \abovedisplayshortskip\abovedisplayskip
    $$\m@th\halign to \linewidth
     \bgroup\@eqnsel\hskip\@centering
      $\displaystyle\tabskip\z@{##}$%
      &\global\@eqcnt\@ne \hskip 2\arraycolsep \hfil${##}$\hfil
      &\global\@eqcnt\tw@ \hskip 2\arraycolsep
         $\displaystyle{##}$\hfil \tabskip\@centering
      &\llap{##}\tabskip\z@\cr}
\def\endsubeqnarray{\@@subeqncr\egroup
                     $$\global\@ignoretrue}
\def\@subeqncr{{\ifnum0=`}\fi\@ifstar{\global\@eqpen\@M
    \@ysubeqncr}{\global\@eqpen\interdisplaylinepenalty \@ysubeqncr}}
\def\@ysubeqncr{\@ifnextchar [{\@xsubeqncr}{\@xsubeqncr[\z@]}}
\def\@xsubeqncr[#1]{\ifnum0=`{\fi}\@@subeqncr
   \noalign{\penalty\@eqpen\vskip\jot\vskip #1\relax}}
\def\@@subeqncr{\let\@tempa\relax
    \ifcase\@eqcnt \def\@tempa{& & &}\or \def\@tempa{& &}
      \else \def\@tempa{&}\fi
     \@tempa \if@eqnsw\@subeqnnum\refstepcounter{subequation}\fi
     \global\@eqnswtrue\global\@eqcnt\z@\cr}
%    \end{macrocode}
% Here's the subeqnarray* environment:
%    \begin{macrocode}
\let\@ssubeqncr=\@subeqncr
\@namedef{subeqnarray*}{\def\@subeqncr{\nonumber\@ssubeqncr}\subeqnarray}
\@namedef{endsubeqnarray*}{\global\advance\c@equation\m@ne%
                           \nonumber\endsubeqnarray}
%    \end{macrocode}
\endinput
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