%<+package>\NeedsTeXFormat{LaTeX2e}
%<+package>\ProvidesPackage{mdwmath}
%<+package> [2020/09/06 1.14.0 Nice mathematical things]
-%<+oldeqnarray>\NeedsTeXFormat{LaTeX2e}
-%<+oldeqnarray>\ProvidesPackage{eqnarray}
-%<+oldeqnarray> [2020/09/06 1.14.0 Old enhanced eqnarray]
% \end{meta-comment}
%
% \CheckSum{728}
\let\opmod\pmod
\usepackage{amssymb}
\describespackage{mdwmath}
-%\describespackage{eqnarray}
-\ignoreenv{old-eqnarray}
-%\unignoreenv{old-eqnarray}
\mdwdoc
%</driver>
%
% the command |\mpunct| sets its argument as text, a little distance from
% the preceding mathematics.
%
-% \begin{ignore}
-% There used to be an eqnarray here, but that's migrated its way into the
-% \package{mdwtab} package. Maybe the original version, without dependency
-% on \package{mdwtab} ought to be releasable separately. I'll keep it around
-% just in case.
-%
-% The following is the documentation for the original version. There's an
-% updated edition in \package{mdwtab}.
-% \end{ignore}
-%
-% \begin{old-eqnarray}
-%
-% \subsection{A new \env{eqnarray} environment}
-%
-% \LaTeX's built-in \env{eqnarray} is horrible -- it puts far too much space
-% between the items in the array. This environment is rather nearer to the
-% \env{amsmath} \env{align} environments, although rather less capable.
-%
-% \bigskip
-% \DescribeEnv{eqnarray}
-% {\synshorts
-% \setbox0\hbox{"\\begin{eqnarray}["<preamble>"]" \dots "\\end{eqnarray}"}
-% \leavevmode \hskip-\parindent \fbox{\box0}
-% }
-% \smallskip
-%
-% The new version of \env{eqnarray} tries to do everything which you really
-% want it to. The \synt{preamble} string allows you to define the column
-% types in a vaguely similar way to the wonderful \env{tabular} environment.
-% The types provided (and it's easy-ish to add more) are:
-%
-% \def\ch{\char`}
-% \begin{description} \setdescriptionlabel{\normalfont\ttfamily#1}
-% \item [r] Right aligned equation
-% \item [c] Centre-aligned equation
-% \item [l] Left aligned equation
-% \item [\textrm{\texttt{Tr}, \texttt{Tc} and \texttt{Tl}}] Right, centre and
-% left aligned text (not maths)
-% \item [L] Left aligned zero-width equation
-% \item [x] Centred entire equation
-% \item [:] Big gap separating sets of equations
-% \item [q] Quad space
-% \item [>\ch\{\synt{text}\ch\}] Insert text before column
-% \item [<\ch\{\synt{text}\ch\}] Insert text after column
-% \end{description}
-%
-% Some others are also defined: don't use them because they do complicated
-% things which are hard to explain and they aren't much use anyway.
-%
-% The default preamble, if you don't supply one of your own, is \lit{rcl}.
-% Most of the time, \lit{rl} is sufficient, although compatibility is more
-% important to me.
-%
-% By default, there is no space between columns, which makes formul\ae\ in an
-% \env{eqnarray} environment look just like formul\ae\ typeset on their own,
-% except that things get aligned in columns. This is where the default
-% \env{eqnarray} falls down: it leaves |\arraycolsep| space between each
-% column making the thing look horrible.
-%
-% An example would be good here, I think. This one's from exercise 22.9 of
-% the \textit{\TeX book}.
-%
-% \begin{demo}[w]{Simultaneous equations}
-%\begin{eqnarray}[rcrcrcrl]
-% 10w & + & 3x & + & 3y & + & 18z & = 1 \\
-% 6w & - & 17x & & & - & 5z & = 2
-%\end{eqnarray}
-% \end{demo}
-%
-% Choosing a more up-to-date example, here's one demonstrating the \lit{:}
-% column specifier from the \textit{\LaTeX\ Companion}.
-%
-% \begin{demo}[w]{Lots of equations}
-%\begin{eqnarray}[rl:rl:l]
-% V_i &= v_i - q_i v_j, & X_i &= x_i - q_i x_j, &
-% U_i = u_i, \qquad \mbox{for $i \ne j$} \label{eq:A} \\
-% V_j &= v_j, & X_j &= x_j &
-% U_j u_j + \sum_{i \ne j} q_i u_i.
-%\end{eqnarray}
-% \end{demo}
-%
-% We can make things more interesting by adding a plain text column. Here we
-% go:
-%
-% \begin{demo}[w]{Plain text column}
-%\begin{eqnarray}[rlqqTl]
-% x &= y & by (\ref{eq:A}) \\
-% x' &= y' & by definition \\
-% x + x' &= y + y' & by Axiom~1
-%\end{eqnarray}
-% \end{demo}
-%
-% The new features also mean that you don't need to mess about with
-% |\lefteqn| any more. This is handled by the \lit{L} column type:
-%
-% \begin{demo}{Splitting example}
-%\begin{eqnarray*}[Ll]
-% w+x+y+z = \\
-% & a+b+c+d+e+{} \\
-% & f+g+h+i+j
-%\end{eqnarray*}
-% \end{demo}
-%
-% Finally, just to prove that the spacing's right at last, here's another one
-% from the \textit{Companion}.
-%
-% \begin{demo}{Spacing demonstration}
-%\begin{equation}
-% x^2 + y^2 = z^2
-%\end{equation}
-%\begin{eqnarray}[rl]
-% x^2 + y^2 &= z^2 \\
-% y^2 &< z^2
-%\end{eqnarray}
-% \end{demo}
-%
-% Well, that was easy enough. Now on to numbering. As you've noticed, the
-% equations above are numbered. You can use the \env{eqnarray$*$}
-% environment to turn off the numbering in the whole environment, or say
-% |\nonumber| on a line to suppress numbering of that one in particular.
-% More excitingly, you can say \syntax{"\\nonumber["<text>"]"} to choose
-% what text to display.
-%
-% A note for cheats: you can use the sparkly new \env{eqnarray} for simple
-% equations simply by specifying \lit{x} as the column description. Who
-% needs \AmSTeX? |;-)|
-%
-% \end{old-eqnarray}
-%
% \implementation
%
% \section{Implementation}
%
%\end{macro}
%
-% \begin{ignore}
-% The following is the original definition of the enhanced eqnarray
-% environment. It's not supported, although if you can figure out how to
-% extract it, it's all yours.
-% \end{ignore}
-%
-% \begin{old-eqnarray}
-%
-% \subsection{The sparkly new \env{eqnarray}}
-%
-% Start off by writing a different package.
-%
-% \begin{macrocode}
-%</package>
-%<*oldeqnarray>
-% \end{macrocode}
-%
-% \subsubsection{Options handling}
-%
-% We need to be able to cope with \textsf{fleqn} and \textsf{leqno} options.
-% This will adjust our magic modified \env{eqnarray} environment
-% appropriately.
-%
-% \begin{macrocode}
-\newif\if@fleqn
-\newif\if@leqno
-\DeclareOption{fleqn}{\@fleqntrue}
-\DeclareOption{leqno}{\@leqnotrue}
-\ProcessOptions
-% \end{macrocode}
-%
-% This is all really different to the \LaTeX\ version. I've looked at the
-% various \env{tabular} implementations, the original \env{eqnarray} and the
-% \textit{\TeX book} to see how best to do this, and then went my own way.
-% If it doesn't work it's all my fault.
-%
-% \subsubsection{Some useful registers}
-%
-% The old \LaTeX\ version puts the equation numbers in by keeping a count of
-% where it is in the alignment. Since I don't know how may columns there are
-% going to be, I'll just use a switch in the preamble to tell me to stop
-% tabbing.
-%
-% \begin{macrocode}
-\newif\if@eqalast
-% \end{macrocode}
-%
-% Now define some useful length parameters. First allocate them:
-%
-% \begin{macrocode}
-\newskip\eqaopenskip
-\newskip\eqacloseskip
-\newskip\eqacolskip
-\newskip\eqainskip
-% \end{macrocode}
-%
-% Now assign some default values. Users can play with these if they really
-% want although I can't see the point myself.
-%
-% \begin{macrocode}
-\if@fleqn
- \AtBeginDocument{\eqaopenskip\leftmargini}
-\else
- \eqaopenskip\@centering
-\fi
-\eqacloseskip\@centering
-\eqacolskip\@centering
-\eqainskip\z@
-% \end{macrocode}
-%
-% We allow the user to play with the style if this is really wanted. I dunno
-% why, really. Maybe someone wants very small alignments.
-%
-% \begin{macrocode}
-\let\eqa@style\displaystyle
-% \end{macrocode}
-%
-% \subsubsection{The main environments}
-%
-% We define the toplevel commands here. They just add in default arguments
-% and then call |\@eqnarray| with a preamble string. The only difference is
-% the last column they add in -- \env{eqnarray$*$} throws away the last
-% column by sticking it in box~0. (I used to |\@gobble| it but that caused
-% the |\cr| to be lost.)
-%
-% \begin{macrocode}
-\def\eqnarray{\@ifnextchar[\eqnarray@i{\eqnarray@i[rcl]}}
-\def\eqnarray@i[#1]{%
- \@eqnarray{#1!{\hb@xt@\z@{\hss##}\tabskip\z@}}
-}
-\@namedef{eqnarray*}{\@ifnextchar[\eqnarray@s@i{\eqnarray@s@i[rcl]}}
-\def\eqnarray@s@i[#1]{%
- \@eqnarray{#1!{\nonumber\setbox\z@\hbox{##}\tabskip\z@}}%
-}
-% \end{macrocode}
-%
-% \subsubsection{Set up the initial display}
-%
-% \begin{macro}{\@eqnarray}
-%
-% The |\@eqnarray| command does most of the initial work. It sets up some
-% flags and things, builds the |\halign| preamble, and returns.
-%
-% \begin{macrocode}
-\def\@eqnarray#1{%
-% \end{macrocode}
-%
-% Start playing with the counter here. The original does some icky internal
-% playing, which isn't necessary. The |\if@eqnsw| switch is |true| if the
-% user hasn't supplied an equation number. The |\if@eqalast| switch is
-% |true| in the final equation-number column.
-%
-% \begin{macrocode}
- \refstepcounter{equation}%
- \@eqalastfalse%
- \global\@eqnswtrue%
- \m@th%
-% \end{macrocode}
-%
-% Set things up for the |\halign| which is coming up.
-%
-% \begin{macrocode}
- \openup\jot%
- \tabskip\eqaopenskip%
- \let\\\@eqncr%
- \everycr{}%
- $$%
-% \end{macrocode}
-%
-% We'll build the real |\halign| and preamble in a token register. All we
-% need to do is stuff the header in the token register, clear a switch
-% (that'll be explained later), parse the preamble and then expand the
-% tokens we collected. Easy, no?
-%
-% \begin{macrocode}
- \toks@{\halign to\displaywidth\bgroup}%
- \@tempswafalse%
- \eqa@preamble#1\end%
- \the\toks@\cr%
-}
-% \end{macrocode}
-%
-% \end{macro}
-%
-% \subsubsection{Parsing the preamble}
-%
-% All this actually involves is reading the next character and building a
-% command from it. That can pull off an argument if it needs it. Just make
-% sure we don't fall off the end and we'll be OK.
-%
-% \begin{macrocode}
-\def\eqa@preamble#1{%
- \ifx\end#1\else\csname eqa@char@#1\expandafter\endcsname\fi%
-}
-% \end{macrocode}
-%
-% Adding stuff to the preamble tokens is a simple matter of using
-% |\expandafter| in the correct way.\footnote{^^A
-% I have no idea why \LaTeX\ uses \cmd\edef\ for building its preamble. It
-% seems utterly insane to me -- the amount of bodgery that \env{tabular}
-% has to go through to make everything expand at the appropriate times is
-% scary. Maybe Messrs~Lamport and Mittelbach just forgot about token
-% registers when they were writing the code. Maybe I ought to rewrite the
-% thing properly some time. Sigh.
-%
-% As a sort of postscript to the above, I \emph{have} rewritten the
-% \env{tabular} environment, and made a damned fine job of it, in my
-% oh-so-humble opinion. All this \env{eqnarray} stuff has been remoulded
-% in terms of the generic column-defining things in \package{mdwtab}.
-% You're reading the documentation of the old version, which isn't
-% supported any more, so any bugs here are your own problem.}
-%
-% \begin{macrocode}
-\def\eqa@addraw#1{\expandafter\toks@\expandafter{\the\toks@#1}}
-% \end{macrocode}
-%
-% Now for some cleverness again. In order to put all the right bits of
-% |\tabskip| glue in the right places we must \emph{not} terminate each
-% column until we know what the next one is. We set |\if@tempswa| to be
-% |true| if there's a column waiting to be closed (so it's initially
-% |false|). The following macro adds a column correctly, assuming we're in
-% a formula. Other column types make their own arrangements.
-%
-% \begin{macrocode}
-\def\eqa@add#1{%
- \if@tempswa%
- \eqa@addraw{\tabskip\eqainskip}%
- \else%
- \eqa@addraw{#1}%
- \fi%
- \@tempswatrue%
-}
-% \end{macrocode}
-%
-% Now to defining column types. Let's define a macro which allows us to
-% define column types:
-%
-% \begin{macrocode}
-\def\eqa@def#1{\expandafter\def\csname eqa@char@#1\endcsname}
-% \end{macrocode}
-%
-% Now we can define the column types. Each column type must loop back to
-% |\eqa@preamble| once it's finished, to read the rest of the preamble
-% string. Note the positioning of ord atoms in the stuff below. This will
-% space out relations and binops correctly when they occur at the edges of
-% columns, and won't affect ord atoms at the edges, because ords pack
-% closely.
-%
-% First the easy onces. Just stick |\hfil| in the right places and
-% everything will be all right.
-%
-% \begin{macrocode}
-\eqa@def r{\eqa@add{\hfil$\eqa@style##{}$}\eqa@preamble}
-\eqa@def c{\eqa@add{\hfil$\eqa@style{}##{}$\hfil}\eqa@preamble}
-\eqa@def l{\eqa@add{$\eqa@style{}##$\hfil}\eqa@preamble}
-\eqa@def x{\eqa@add{\hfil$\eqa@style##$\hfil}\eqa@preamble}
-% \end{macrocode}
-%
-% Now for the textual ones. This is also fairly easy.
-%
-% \begin{macrocode}
-\eqa@def T#1{%
- \eqa@add{}%
- \if#1l\else\eqa@addraw{\hfil}\fi%
- \eqa@addraw{##}%
- \if#1r\else\eqa@addraw{\hfil}\fi%
- \eqa@preamble%
-}
-% \end{macrocode}
-%
-% Sort of split types of equations. I mustn't use |\rlap| here, or
-% everything goes wrong -- |\\| doesn't get noticed by \TeX\ in the same way
-% as |\cr| does.
-%
-% \begin{macrocode}
-\eqa@def L{\eqa@add{\hb@xt@\z@{$\eqa@style##$\hss}\qquad}\eqa@preamble}
-% \end{macrocode}
-%
-% The \lit{:} column type is fairly simple. We set |\tabskip| up to make
-% lots of space and close the current column, because there must be one.^^A
-% \footnote{This is an assumption.}
-%
-% \begin{macrocode}
-\eqa@def :{%
- \eqa@addraw{\tabskip\eqacolskip&}\@tempswafalse\eqa@preamble%
-}
-\eqa@def q{\eqa@add{\quad}\@tempswafalse\eqa@preamble}
-% \end{macrocode}
-%
-% The other column types just insert given text in an appropriate way.
-%
-% \begin{macrocode}
-\eqa@def >#1{\eqa@add{#1}\@tempswafalse\eqa@preamble}
-\eqa@def <#1{\eqa@addraw{#1}\eqa@preamble}
-% \end{macrocode}
-%
-% Finally, the magical \lit{!} column type, which sets the equation number.
-% We set up the |\tabskip| glue properly, tab on, and set the flag which
-% marks the final column.
-%
-% \begin{macrocode}
-\eqa@def !#1{%
- \eqa@addraw{\tabskip\eqacloseskip&\@eqalasttrue#1}\eqa@preamble%
-}
-% \end{macrocode}
-%
-% \subsubsection{Newline codes}
-%
-% Newline sequences (|\\|) get turned into calls of |\@eqncr|. The job is
-% fairly simple, really. However, to avoid reading `|&|' characters
-% prematurely, we set up a magic brace (from the \package{array} package --
-% this avoids creating ord atoms and other nastyness).
-%
-% \begin{macrocode}
-\def\@eqncr{%
- \iffalse{\fi\ifnum0=`}\fi%
- \@ifstar{\eqacr@i{\@M}}{\eqacr@i{\interdisplaylinepenalty}}%
-}
-\def\eqacr@i#1{\@ifnextchar[{\eqacr@ii{#1}}{\eqacr@ii{#1}[\z@]}}
-\def\eqacr@ii#1[#2]{%
- \ifnum0=`{}\fi%
- \eqa@eqnum%
- \noalign{\penalty#1\vskip#2\relax}%
-}
-% \end{macrocode}
-%
-% \subsubsection{Setting equation numbers}
-%
-% Before we start, we need to generalise the flush-left number handling bits.
-% The macro |\eqa@eqpos| will put its argument in the right place.
-%
-% \begin{macrocode}
-\if@leqno
- \def\eqa@eqpos#1{%
- \hb@xt@.01\p@{}\rlap{\normalfont\normalcolor\hskip-\displaywidth#1}%
- }
-\else
- \def\eqa@eqpos#1{\normalfont\normalcolor#1}
-\fi
-% \end{macrocode}
-%
-% First we need to move into the right column. Then we just set the equation
-% number appropriately. There is some subtlety here, ish. The |\relax| is
-% important, to delay expansion of the |\if|\dots\ until the new column has
-% been started. The two helper macros are important too, to hide `|&|'s and
-% `|\cr|'s from \TeX's scanner until the right time.
-%
-% \begin{macrocode}
-\def\eqa@eqnum{%
- \relax%
- \if@eqalast\expandafter\eqa@eqnum@i\else\expandafter\eqa@eqnum@ii\fi%
-}
-\def\eqa@eqnum@i{%
- \if@eqnsw%
- \eqa@eqpos{(\theequation)}\stepcounter{equation}%
- \else%
- \eqa@eqpos\eqa@number%
- \fi%
- \global\@eqnswtrue%
- \cr%
-}
-\def\eqa@eqnum@ii{&\eqa@eqnum}
-% \end{macrocode}
-%
-% \subsubsection{Numbering control}
-%
-% This is trivial. We set the |\if@eqnsw| flag to be |false| and store the
-% text in a macro.
-%
-% \begin{macrocode}
-\let\nonumber\relax
-\newcommand\nonumber[1][]{\global\@eqnswfalse\global\def\eqa@number{#1}}
-% \end{macrocode}
-%
-% \subsubsection{Closing the environments off}
-%
-% This is really easy. Set the final equation number, close the |\halign|,
-% tidy up the equation counter (it's been stepped once too many times) and
-% close the display.
-%
-% \begin{macrocode}
-\def\endeqnarray{%
- \eqa@eqnum%
- \egroup%
- \global\advance\c@equation\m@ne%
- $$%
- \global\@ignoretrue%
-}
-\expandafter\let\csname endeqnarray*\endcsname\endeqnarray
-% \end{macrocode}
-%
-% Now start up the other package again.
-%
-% \begin{macrocode}
-%</oldeqnarray>
-%<*package>
-% \end{macrocode}
-%
-% \end{old-eqnarray}
-%
% That's all there is. Byebye.
%
% \begin{macrocode}
~mdw / mdwtools / commitdiff