[latexrefmancommits] r404  in /trunk: ChangeLog latex2e.texi
jhefferon at domain.hid
jhefferon at domain.hid
Tue Aug 18 19:07:11 CEST 2015
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 @@
+20150818 Jim Hefferon <jhefferon at domain.hid>
+
+ * latex2e.texi (eqnarray, equation): Add more description. Add
+ example to eqnarray. Add note about amsmath to equation.
+
20150817 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 flushleft 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/tb331/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/tb331/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 threecolumn
 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 threecolumn @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
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