latex2e-20170415/required/amsmath/subeqn.tex

   1 %%% ====================================================================
   2 %%%  @LaTeX-file{
   3 %%%     filename  = "subeqn.tex",
   4 %%%     version   = "1.2c",
   5 %%%     date      = "1999/11/29",
   6 %%%     time      = "14:49:29 EST",
   7 %%%     checksum  = "29866 202 668 6426",
   8 %%%     author    = "American Mathematical Society",
   9 %%%     copyright = "Copyright 1999 American Mathematical Society,
  10 %%%                  all rights reserved.  Copying of this file is
  11 %%%                  authorized only if either:
  12 %%%                  (1) you make absolutely no changes to your copy,
  13 %%%                  including name; OR
  14 %%%                  (2) if you do make changes, you first rename it
  15 %%%                  to some other name.",
  16 %%%     address   = "American Mathematical Society,
  17 %%%                  Technical Support,
  18 %%%                  Electronic Products and Services,
  19 %%%                  P. O. Box 6248,
  20 %%%                  Providence, RI 02940,
  21 %%%                  USA",
  22 %%%     telephone = "401-455-4080 or (in the USA and Canada)
  23 %%%                  800-321-4AMS (321-4267)",
  24 %%%     FAX       = "401-331-3842",
  25 %%%     email     = "tech-support@ams.org (Internet)",
  26 %%%     supported = "yes",
  27 %%%     keywords  = "latex, amslatex, ams-latex, amstex",
  28 %%%     abstract  = "This is part of the AMS-\LaTeX{} distribution.
  29 %%%                  It is a sample document illustrating the use of
  30 %%%                  the subequations environment and the effect of
  31 %%%                  the fleqn option.",
  32 %%%     docstring = "The checksum field above contains a CRC-16
  33 %%%                  checksum as the first value, followed by the
  34 %%%                  equivalent of the standard UNIX wc (word
  35 %%%                  count) utility output of lines, words, and
  36 %%%                  characters.  This is produced by Robert
  37 %%%                  Solovay's checksum utility.",
  38 %%%  }
  39 %%% ====================================================================
  40 \documentclass[fleqn]{article}
  41
  42 \title{Test of subequations environment}
  43 \author{mjd}
  44
  45 \usepackage{amsmath}
  46 \numberwithin{equation}{section}
  47
  48 \newcommand{\env}[1]{{\normalfont\texttt{#1}}}
  49
  50 \AtEndDocument{\multipasswarning}
  51 \newcommand{\multipasswarning}{%
  52   \clearpage
  53   \typeout{%
  54   **********************************************************************}
  55   \typeout{%
  56   Note: This document needs to run through LaTeX three times, instead of}
  57   \typeout{%
  58   the usual two, to resolve indirect cross-references.}
  59   \typeout{%
  60   **********************************************************************}
  61 }
  62
  63 \makeatletter
  64 %    Omit the warning message if three passes have been completed (on
  65 %    first pass \ref{check} is undefined and it is set to 0; on second
  66 %    pass \ref{check} is 0 and set to 1; on third pass it is 1).
  67 \def\checkref{\begingroup
  68   \@ifundefined{r@check}{\def\@currentlabel{0}}{\def\@currentlabel{1}}%
  69   \ifnum1=0\expandafter\@firstoftwo\r@check\relax
  70     \global\let\multipasswarning\relax
  71   \fi
  72   \label{check}%
  73   \endgroup}
  74 \makeatother
  75
  76 \begin{document}
  77 \section{Prime equation numbers}
  78
  79 First an equation.
  80 \begin{equation}\label{e:previous}
  81 A=B
  82 \end{equation}
  83 That was equation \eqref{e:previous}.
  84
  85 Then the same, with a prime on the number.\checkref
  86 \begin{equation}
  87 \tag{\ref{e:previous}$'$}\label{e:prevprime}
  88 C=D
  89 \end{equation}
  90 And that was equation \eqref{e:prevprime}.
  91
  92 Notice, by the way, that when a \verb"\ref" occurs inside a \verb"\tag",
  93 and that \verb"\tag" is then \verb"\label"'d, a \verb"\ref" for the the
  94 second \verb"\label" requires \emph{three} runs of \LaTeX{} in order to
  95 get the proper value. (If you run through the logic of \LaTeX{}'s
  96 cross-referencing mechanisms as they apply in this case, you will see
  97 that this is necessary.)
  98
  99 \section{Subnumbered equations}
 100
 101 Here is a,b,c sub-numbering.
 102 \begin{subequations}
 103 \begin{eqnarray}
 104 A&=&B\\
 105 D&=&C \label{e:middle}\\
 106 E&=&F
 107 \end{eqnarray}
 108 \end{subequations}
 109 That was produced with the \env{eqnarray} environment; the middle line
 110 was labeled as \eqref{e:middle}.
 111
 112 An equation following the end of the \verb"subequations" environment
 113 should revert to normal numbering:
 114 \begin{equation}\label{e:check}
 115 H<K
 116 \end{equation}
 117 A check on the labeling: that was equation~\eqref{e:check}.
 118
 119 The sub-numbered equations can be spread out through the text, like
 120 this:
 121 \begin{subequations}
 122 \begin{equation}
 123 A=B
 124 \end{equation}
 125 The \verb"subequations" environment can span arbitrary text between
 126 subsidiary equations. The only restriction is that if there are any
 127 numbered equations inside the \verb"subequations" environment that break
 128 out of the subequation numbering sequence, they would have to be handled
 129 specially.
 130 \begin{equation}
 131 D=C \label{e:newmiddle}
 132 \end{equation}
 133 More arbitrary text.
 134 \begin{equation}
 135 E=F
 136 \end{equation}
 137 \end{subequations}
 138 Label check: the middle one was \eqref{e:newmiddle}
 139
 140 A final equation for a numbering check.
 141 \begin{equation}\label{e:final}
 142 G=H
 143 \end{equation}
 144 That equation was labeled as \eqref{e:final}.
 145
 146 \section{Tests of \env{align}, \env{gather}, and other
 147 AMS-\protect\LaTeX{} environments}
 148
 149 The \env{align} environment:
 150 \begin{subequations}
 151 \begin{align}
 152 \label{align:a}A+B&=B+A\\
 153 \label{align:b}C&=D+E\\
 154 \label{align:c}E&=F
 155 \end{align}
 156 \end{subequations}
 157 Label check: that was \eqref{align:a}, \eqref{align:b}, and
 158 \eqref{align:c}.
 159
 160 The \env{align} environment again:
 161 \begin{subequations}
 162 \begin{align}
 163 \label{xalign:a}A+B&=B&     B&=B+A\\
 164 \label{xalign:b}C&=D+E&     C\oplus D&=E\\
 165 \label{xalign:c}E&=F&       E'&=F'
 166 \end{align}
 167 \end{subequations}
 168 Label check: that was \eqref{xalign:a}, \eqref{xalign:b}, and
 169 \eqref{xalign:c}.
 170
 171 The \env{gather} environment. For the third line we refer to one of the
 172 numbers in the first \env{align} structure.
 173 \begin{subequations}
 174 \begin{gather}
 175 \label{gather:a}A+B=B\\
 176 \label{gather:b}C=D+E\\
 177 \tag{\ref{align:c}$'$}\label{gather:c}E=F
 178 \end{gather}
 179 \end{subequations}
 180 Label check: that was \eqref{gather:a},
 181 \eqref{gather:b}, and
 182 \eqref{gather:c}.
 183
 184 The next \env{subequations} environment encompasses two separate
 185 equations. A \env{split} environment:
 186 \begin{subequations}
 187 \begin{equation}
 188 \label{split:x}
 189 \begin{split}
 190 A&=B+C+F\\
 191 &=G
 192 \end{split}
 193 \end{equation}
 194 and a \env{multline} environment:
 195 \begin{multline}\label{multline:x}
 196 A[B]C[D]E[F]G[[H[I]J[K]L[M]N]]=\\
 197 H[I]J[K]L[M]N[O]P[Q]R[S]T[U]V[W]X[Y]Z
 198 \end{multline}
 199 \end{subequations}
 200 Label check: That was \eqref{split:x} and \eqref{multline:x}.
 201
 202 \end{document}