[latexrefman-commits] r404 - in /trunk: ChangeLog latex2e.texi

[jhefferon at domain.hid]

Author: jhefferon
Date: Tue Aug 18 19:07:11 2015
New Revision: 404

URL: http://svn.gna.org/viewcvs/latexrefman?rev=404&view=rev
Log:
eqnarray, equation

Modified:
    trunk/ChangeLog
    trunk/latex2e.texi

Modified: trunk/ChangeLog
URL: http://svn.gna.org/viewcvs/latexrefman/trunk/ChangeLog?rev=404&r1=403&r2=404&view=diff
==============================================================================
--- trunk/ChangeLog	(original)
+++ trunk/ChangeLog	Tue Aug 18 19:07:11 2015
@@ -1,3 +1,8 @@
+2015-08-18  Jim Hefferon  <jhefferon at domain.hid>
+
+	* latex2e.texi (eqnarray, equation): Add more description.  Add
+	example to eqnarray.  Add note about amsmath to equation.
+
 2015-08-17  Jim Hefferon  <jhefferon at domain.hid>
 
 	* latex2e.texi (enumerate): Add more description. Combine best

Modified: trunk/latex2e.texi
URL: http://svn.gna.org/viewcvs/latexrefman/trunk/latex2e.texi?rev=404&r1=403&r2=404&view=diff
==============================================================================
--- trunk/latex2e.texi	(original)
+++ trunk/latex2e.texi	Tue Aug 18 19:07:11 2015
@@ -2032,12 +2032,16 @@
 and centered.  To make the text be flush-left use the global option
 @code{fleqn}; see @ref{Document class options}.
 
+ at LaTeX{} will not break the math text across lines.
+
 In the @code{displaymath} environment no equation number is added to the
 math text. One way to get an equation number is to use the
 @code{equation} environment (@pxref{equation}).
 
-The @file{amsmath} package has extensive displayed equation facilities.
-Those facilities are the best approach for such output in new documents.
+Note that the @file{amsmath} package has extensive displayed equation
+facilities.  Those facilities are the best approach for such output in
+new documents.  For example, there are a number of options in that
+package for having math text broken across lines.
 
 The construct @code{\[..math text..\]} is essentially a synonym for
 @code{\begin at domain.hid text..\end at domain.hid@}} but the
@@ -2214,46 +2218,69 @@
 @cindex align @r{environment, from @code{amsmath}}
 @cindex amsmath @r{package, replacing @code{eqnarray}}
 @cindex Madsen, Lars
-First, a caveat: the @code{eqnarray} environment has some infelicities
-which cannot be overcome; the article ``Avoid eqnarray!''@: by Lars
-Madsen describes them in detail
-(@url{http://tug.org/TUGboat/tb33-1/tb103madsen.pdf}).  The bottom
-line is that it is better to use the @code{align} environment (and
-others) from the @code{amsmath} package.
-
-Nevertheless, here is a description of @code{eqnarray}:
-
- at domain.hid
-\begin at domain.hid@}  @r{(or @code{eqnarray*})}
- at domain.hid} \\
- at domain.hid} \\
-...
+First, a caveat: the @code{eqnarray} environment is depreciated.  It has
+infelicities that cannot be overcome, including spacing that is
+inconsistent with other mathematics elements (see the article ``Avoid
+eqnarray!''@: by Lars Madsen
+ at url{http://tug.org/TUGboat/tb33-1/tb103madsen.pdf}).  New documents
+should include the @file{amsmath} package and use the displayed
+mathematics environments provided there, such as the @code{align}
+environment.
+
+Nevertheless, for completeness and for a reference when working with old
+documents, a synopsis:
+
+ at example
+\begin at domain.hid@} 
+  @var{first formula left}  &@var{first formula middle}  &@var{first formula right} \\
+  ...
 \end at domain.hid@}
 @end example
 
+or 
+
+ at example
+\begin at domain.hid*@} 
+  @var{first formula left}  &@var{first formula middle}  &@var{first formula right} \\
+  ...
+\end at domain.hid*@}
+ at end example
+
 @findex \\ @r{(for @code{eqnarray})}
-The @code{eqnarray} environment is used to display a sequence of
-equations or inequalities.  It is similar to a three-column
- at domain.hid} environment, with consecutive rows separated by @code{\\}
-and consecutive items within a row separated by an @code{&}.
-
+Display a sequence of equations or inequalities.  The left and right
+sides are typeset in display mode, while the middle is typeset in text
+mode.
+
+It is similar to a three-column @code{array} environment, with items
+within a row separated by an ampersand at domain.hid{&}), and with rows
+separated by double backslash at domain.hid{} @code{\\}).
 @findex \\* @r{(for @code{eqnarray})}
- at domain.hid{\\*} can also be used to separate equations, with its normal
-meaning of not allowing a page break at that line.
+The starred form of line break (@code{\\*}) can also be used to separate
+equations, and will disallow a page break there (@pxref{\\}).
 
 @findex \nonumber
 @cindex equation numbers, omitting
-An equation number is placed on every line unless that line has a
- at domain.hid} command.  Alternatively, The @code{*}-form of the
-environment (@code{\begin at domain.hid*@} ... \end at domain.hid*@}}) will
-omit equation numbering entirely, while otherwise being the same as
- at domain.hid}.
+The unstarred form @code{eqnarray} places an equation number on every
+line (using the @code{equation} counter), unless that line contains a
+ at code{\nonumber} command.  The starred form @code{eqnarray*} omits
+equation numbering, while otherwise being the same.
 
 @findex \lefteqn
 The command @code{\lefteqn} is used for splitting long formulas across
 lines. It typesets its argument in display style flush left in a box of
 zero width.
 
+This example shows three lines.  The first two lines make an inequality,
+while the third line has not entry on the left side.
+
+ at example
+\begin at domain.hid*@}
+  \lefteqn at domain.hid@}     \\
+    &\leq &y_1+y_2+\cdots+y_n      \\
+    &=    &z+y_3+\cdots+y_n
+\end at domain.hid*@}
+ at end example
+
 
 @node equation
 @section @code{equation}
@@ -2266,13 +2293,18 @@
 
 @example
 \begin at domain.hid@}
- at domain.hid}
+  .. math text ..
 \end at domain.hid@}
 @end example
 
-The @code{equation} environment starts a @code{displaymath}
-environment (@pxref{displaymath}), e.g., centering the @var{math} text
-on the page, and also places an equation number in the right margin.
+Start a @code{displaymath} environment (@pxref{displaymath}) and also
+place an equation number in the right margin.
+
+The equation number is generated using the @code{equation} counter.
+
+Note that the @file{amsmath} package has extensive displayed equation
+facilities.  Those facilities are the best approach for such output in
+new documents.
 
 
 @node figure