summaryrefslogtreecommitdiff
path: root/Master/texmf-dist/doc/generic/FAQ-en/faq-wdidt.tex
diff options
context:
space:
mode:
authorKarl Berry <karl@freefriends.org>2013-06-28 22:26:18 +0000
committerKarl Berry <karl@freefriends.org>2013-06-28 22:26:18 +0000
commit98d97883f83dd86032b6b058692d87b9fa83926b (patch)
tree8de3c144ec825fc9cc4b1fe255b60875a8b9e1bb /Master/texmf-dist/doc/generic/FAQ-en/faq-wdidt.tex
parentaa0b340189383ff3014db4eaec3aeb58687d6207 (diff)
FAQ-en (7jun13)
git-svn-id: svn://tug.org/texlive/trunk@31019 c570f23f-e606-0410-a88d-b1316a301751
Diffstat (limited to 'Master/texmf-dist/doc/generic/FAQ-en/faq-wdidt.tex')
-rw-r--r--Master/texmf-dist/doc/generic/FAQ-en/faq-wdidt.tex37
1 files changed, 19 insertions, 18 deletions
diff --git a/Master/texmf-dist/doc/generic/FAQ-en/faq-wdidt.tex b/Master/texmf-dist/doc/generic/FAQ-en/faq-wdidt.tex
index ac786c10aab..97ab75e31a9 100644
--- a/Master/texmf-dist/doc/generic/FAQ-en/faq-wdidt.tex
+++ b/Master/texmf-dist/doc/generic/FAQ-en/faq-wdidt.tex
@@ -1739,35 +1739,32 @@ the problem.
\item[AMSLaTeX]\CTANref{amslatex}
\end{ctanrefs}
-\Question[Q-dolldoll]{Why use \csx{[}\,\dots{}\csx{]} in place of \texttt{\$\$}\,\dots{}\texttt{\$\$}?}
+\Question[Q-dolldoll]{Why use \csx{[}\,\dots{}\csx{]} in place of \texttt{\$\$}\,\dots{}\,\texttt{\$\$}?}
\LaTeX{} defines inline- and display-maths commands, apparently
-duplicating those that derive from the \TeX{} primitive maths
-sequences, that maths commands with single (or pairs of) dollar signs.
+duplicating the \TeX{} primitive maths sequences which surround maths
+commands with single (or pairs of) dollar signs.
-As it turns out, \LaTeX{}'s inline maths grouping, % !line break
-\csx{(}\texttt{ ... }\csx{)}, has precisely the same effect as the
-\TeX{} primitive version \texttt{\$ ... \$}. (Except that
+In fact, \LaTeX{}'s inline maths grouping, % !line break
+\csx{(}\texttt{ ... }\csx{)}, has (almost) exactly the same effect as the
+\TeX{} primitive version \texttt{\$ ... \$}. (The exception:
the \LaTeX{} version checks to ensure you don't put \csx{(} and
\csx{)} the wrong way round; this does occasionally detect errors\dots{}.)
Since this is the case, one often finds \LaTeX{} users, who have some
experience of using \plaintex{}, merely assuming that \LaTeX{}'s
display maths grouping \csx{[}\texttt{ ... }\csx{]} may be replaced by
-the \TeX{} primitive display maths \texttt{\$\$ ... \$\$}. Some
-people ``go the whole hog'' and use \cmdinvoke{begin}{displaymath}
-\dots{} \cmdinvoke{end}{displaymath} (which ``looks nicer'', in some
-sense, and actually \emph{describes} what's being done.
-
-Unfortunately, they are wrong: if \LaTeX{} code is going to patch display
-maths, it can only do so by patching \csx{[} and \csx{]}. The most
-obvious way this turns up, is that the class option \pkgoption{fleqn}
+the \TeX{} primitive display maths \texttt{\$\$ ... \$\$}.
+
+Unfortunately, the assumption is wrong: some \LaTeX{} code needs to
+patch display maths, it can only do so by patching \csx{[} and \csx{]}
+(or their equivalents). Most obviously, the class option \pkgoption{fleqn}
simply does not work for equations coded using % ! line break
\texttt{\$\$ ... \$\$}, whether you're using the standard classes
alone, or using package \Package{amsmath}. Also, the \csx{[} and
-\csx{]} construct has code for rationalising vertical spacing in some extreme
-cases; that code is not provided \texttt{\$\$ ... \$\$}, so if you
-use the non-standard version, you may occasionally observe
+\csx{]} construct has code for rationalising vertical spacing in some
+extreme cases; that code is not provided \texttt{\$\$ ... \$\$}, so if
+you use the \plaintex{} version, you may occasionally observe
inconsistent vertical spacing. Similar behaviour can bite if you are
writing a \emph{proof}; placing the ``\acro{QED} symbol'' doesn't work
if it is in \texttt{\$\$}-displayed maths.
@@ -1776,7 +1773,11 @@ There are more subtle effects (especially with package
\Package{amsmath}), and the simple rule is ``use % ! line break
\csx{[}\texttt{ ... }\csx{]} (at least) whenever displayed maths is
needed in \LaTeX{}''.
-\LastEdit{2013-02-20}
+
+(Note that the sequence \csx{[}\texttt{ ... }\csx{]} is duplicated by
+the \environment{displaymath} environment, which can be said to ``look
+nicer'', and actually \emph{describes} what's being done.)
+\LastEdit{2013-06-05}
\Question[Q-2letterfontcmd]{What's wrong with \csx{bf}, \csx{it}, etc.?}