summaryrefslogtreecommitdiff
path: root/Master/texmf-dist/tex/latex/ltxmisc/cases.sty
blob: b82f010a02af8f45615088d89897837bc9ba2ec7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
%  C A S E S . S T Y             ver 2.5    May 2002
%
%  Copyright (C) 1993,1994,1995,2000,2002 by Donald Arseneau
%                                       asnd@triumf.ca
%  These macros may be freely transmitted, reproduced, or modified 
%  provided that this notice is left intact.  Sub-equation numbering
%  is based on subeqn.sty by Stephen Gildea; most of the rest is based
%  on LaTeX's \eqnarray by Leslie Lamport and the LaTeX3 team.
%
%  This provides a LaTeX environment {numcases} to produce multi-case 
%  equations with a separate equation number for each case.  There is
%  also {subnumcases} which numbers each case with the overall equation
%  number plus a letter [8a, 8b, etc.].   The syntax is
%
%  \begin{numcases}{left_side}
%   case_1 & explanation_1 \\
%   case_2 & explanation_2 \\
%   ...
%   case_n & explanation_n
%  \end{numcases}
% 
%  Each case is a math formula, and each explanation is a piece of lr mode
%  text (which may contain math mode in \(...\) or $...$).  The explanations
%  are optional.  Equation numbers are inserted automatically, just as for
%  the eqnarray environment.  In particular, the \nonumber command suppresses
%  an equation number and the \label command allows reference to a particular 
%  case.  In a subnumcases environment, a \label in the left_side of the 
%  equation gives the overall equation number, without any letter. 
%
%  To use this package, 
%  include  "\usepackage{cases}"  after \documentclass.  You may also
%  specify  "\usepackage[subnum]{cases}"  to force *all* numcases 
%  environments to be treated as subnumcases.
%
%  Question: Is there a {numcases*} environment for unnumbered cases?
%  Answer: There is a {cases} environment in AMS-LaTeX, but it is just as
%  convenient to stick with the canonical LaTeX array:
%  \[ left side = \left\{ \begin{array}...\end{array} \right. \]
%
%  Speaking of AMS-math, they use an entirely different system of equation
%  numbering, and this package uses ordinary LaTeX numbering.
%
% - - - - - 
%  A simple example is:
%    \begin{numcases}{|x|=}
%    x, & for $x \geq 0$\\
%    -x, & for $x < 0$
%    \end{numcases}
%
%  Giving:
%                    / x   for x > 0              (1)
%             |x| = <            -
%                    \ -x  for x < 0              (2)
% 
% - - - - -   
%
% Another example is calculating the square root of $c+id$. First compute
% \begin{subnumcases}{\label{w} w\equiv}
%  0    & $c = d = 0$\label{wzero}\\
% \sqrt{|c|}\,\sqrt{\frac{1 + \sqrt{1+(d/c)^2}}{2}}   & $|c| \geq |d|$ \\
% \sqrt{|d|}\,\sqrt{\frac{|c/d| + \sqrt{1+(c/d)^2}}{2}}   & $|c| < |d|$
% \end{subnumcases}
% Then, using $w$ from eq.~(\ref{w}), the square root is
% \begin{subnumcases}{\sqrt{c+id}=}
% 0                    & $w=0$ (case \ref{wzero})\\
% w+i\frac{d}{2w}      & $w \neq 0$, $c \geq 0$ \\
% \frac{|d|}{2w} + iw  & $w \neq 0$, $c < 0$, $d \geq 0$ \\
% \frac{|d|}{2w} - iw  & $w \neq 0$, $c < 0$, $d < 0$ 
% \end{subnumcases}     
%
%  - - -  begin definitions - - - 
 
\ProvidesPackage{cases}[2002/05/02 ver 2.5 ]

\newenvironment{numcases}[1]%
{$$\numc@opts \setbox\z@\hbox
  {\advance\c@equation\@ne\def\@currentlabel{\p@equation\theequation}% local
  $\displaystyle {#1\null}\m@th$}%
 \numc@setsub 
 \setbox\tw@\vbox\bgroup
  \stepcounter{equation}\def\@currentlabel{\p@equation\theequation}% 
  \global\@eqnswtrue\m@th \everycr{}\tabskip\numc@left\let\\\@eqncr
  \halign to\dimen@ii \bgroup \kern\wd\z@ \kern14\p@ % assume width of brace
    \tabskip\z@skip \global\@eqcnt\@ne $\displaystyle{##}$\hfil 
   &\global\@eqcnt\tw@ \skip@10\p@ \advance\skip@\tw@\arraycolsep \hskip\skip@
    ##\unskip\hfil\tabskip\@centering% \unskip removes space if no explanations
   &\global\@eqcnt\thr@@\hbox to\z@\bgroup\hss##\egroup\tabskip\z@skip\cr
}{\@@eqncr \egroup % end \halign, which does not contain first column or brace
 \global\advance\c@equation\m@ne 
%Measure the natural width of the alignment
 \unskip\unpenalty\unskip\unpenalty \setbox\z@\lastbox % grab last line
 \nointerlineskip \copy\z@ % then put it back
 \global\dimen@i\wd\z@ 
 \setbox\z@\hbox{\hskip-\numc@left\unhbox\z@}% Measure its natural width
 \ifdim \wd\z@<\dimen@i \global\dimen@i\wd\z@ \fi
\egroup% end \vbox (box\tw@, box\z@ is restored to LHS)
\hbox to\dimen@ii{\m@th % assemble the whole equation
  \hskip\numc@left 
  \hbox to\dimen@i{$\displaystyle \box\z@ % parameter #1
    \dimen@\ht\tw@ \advance\dimen@\dp\tw@ % get size of brace
    \left\{\vcenter to\dimen@{\vfil}\right.\n@space % make brace
    $\hfil}\hskip\@centering % finished first part (filled whole line)
  \kern-\dimen@ii % backspace the full width
  $\vcenter{\box\tw@}$% overlay the alignment
 }% end the \hbox to\dimen@ii
\numc@resetsub
$$\global\@ignoretrue}

\let\numc@setsub\relax
\let\numc@resetsub\relax

\def\subnumcases{\let\numc@setsub\subequations 
   \let\numc@resetsub\endsubequations  \numcases}
\let\endsubnumcases\endnumcases 

% declare subequations -- either defining them following the style of
% Gildea's subeqn.sty, or using the syntax of AMS-LaTeX if that is loaded.

\@ifundefined{c@parentequation}{% No AMS, define subequations from scratch:
%
% These versions of subequations follow the style of Gildea's subeqn.sty,
% but are thoroughly rewritten.  
%
% You can change the labelling by redefining \thesubequation, but the names
% of the counters may be confusing: The sub-number is given by counter
% {equation}, while the overall equation number is given by {mainequation}.
% There are two ways to reference the overall equation number:
% through the value of \c@mainequation, as in \Roman{mainequation}, or
% through \themainequation, which gives the text of the normal \theequation.
% Refer to the local sub-number with \c@equation, as in \alph{equation}.
% The default numbering is like 13c, given by:
%
\def\thesubequation{\themainequation\alph{equation}}
%
% Some alternatives:
%   \def\thesubequation{\themainequation.\Alph{equation}}  %  13.C
%   \def\thesubequation{\themainequation-\roman{equation}}  %  13-iii
%   \def\thesubequation{(\arabic{mainequation}\alph{equation})} % (13c)
% The third alternative should be used if a document style has
% declared  \renewcommand{\@eqnnum}{\theequation} and
% \renewcommand{\theequation}{(\arabic{equation})}, which makes
% \ref put parentheses around regular equation numbers automatically.
%
\def\subequations{\refstepcounter{equation}%
  \mathchardef\c@mainequation\c@equation
  \let\@tempa\protect % * added protection
  \def\protect{\noexpand\protect\noexpand}% *
  \edef\themainequation{\theequation}\let\theequation\thesubequation
  \let\protect\@tempa % *
  \global\c@equation\z@}
%
\def\endsubequations{%
  \global\c@equation\c@mainequation
  \global\@ignoretrue}
%
% \begin{subeqnarray}  works like  \begin{subequations}\begin{eqnarray},
% with the added feature that a \label command given given at the very
% beginning of the first entry defines a label for the overall equation 
% number.
%
\def\subeqnarray{\subequations\eqnarray\@ifnextchar\label{\@lab@subeqnarray}{}}
\def\endsubeqnarray{\endeqnarray\endsubequations}
\def\@lab@subeqnarray#1#2{\begingroup 
  \let\@currentlabel\themainequation #1{#2}\endgroup}
%
}{}% AMS \subequations already defined 

\def\numc@left{\@centering}
\def\numc@opts{\dimen@ii\displaywidth}

\DeclareOption{subnum}{
  \let\numc@setsub\subequations 
  \let\numc@resetsub\endsubequations }

\DeclareOption{fleqn}{
  \def\numc@left{\mathindent}
  \def\numc@opts{\displaywidth\linewidth 
  \dimen@ii\linewidth }
}
\ProcessOptions 

\endinput

% Send problem reports to asnd@triumf.ca

Test file integrity:  ASCII 32-57, 58-126:  !"#$%&'()*+,-./0123456789
:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~