2

When I use \index, everything is ok, but when I use \newcommand instead, some large symbols can not show:

\documentclass[a4paper,openany,12pt]{amsbook}
\usepackage{imakeidx}
\makeindex[name = index, title = Special Index, columns = 3]
%--------------------------------------------------------
\newcommand{\khm}[1]{#1\index[index]{{#1}}}
%--------------------------------------------------------
\begin{document}
\khm{$\bigcup$} \khm{$<$}
\printindex[index]
\end{document}

The above just show $<$ not $\bigcup$. Could you please help?

1 Answer 1

1

If you look in index.idx, which is what LaTeX writes out for later being processed by MakeIndex, you find

\indexentry{{$\DOTSB \bigcup@ \slimits@ $}}{1}
\indexentry{{$<$}}{1}

What happens? When \index is found at the outer level, it enters a “semiverbatim” mode, so \index{$\bigcup$} would write

\indexentry{$\bigcup$}{1}

In particular, what's passed to the eventual \write operation is the string of characters \bigcup, not a command.

In your case, instead, the tokens $\bigcup$ have already been formed and the “semiverbatim” mode can do nothing. And TeX will perform macro expansion during \write.

Solution:

\documentclass[a4paper,openany,12pt]{amsbook}
\usepackage{imakeidx}

\makeindex[name = index, title = Special Index, columns = 3]

\newcommand{\khm}[1]{#1\index[index]{\unexpanded{\unexpanded{#1}}}}

\begin{document}

\khm{$\bigcup$} \khm{$<$}

\printindex[index]

\end{document}

You need two \unexpanded, because TeX would try expansion twice.

The contents of the .idx file is now

\indexentry{$\bigcup $}{1}
\indexentry{$<$}{1}

and the .ind file will be

\begin{theindex}

  \item $<$, 1
  \item $\bigcup $, 1

\end{theindex}

Regarding \exists!, you have to take into account that ! is a special character for MakeIndex and has to be quoted. You might go with

\newcommand{\khm}[1]{%
  \begingroup\mathcode`"="8000\relax
  \begingroup\lccode`~=`"\lowercase{\endgroup\let~}\relax
  #1\endgroup\index[index]{\unexpanded{\unexpanded{#1}}}}

so that

\khm{$\exists"!$}

would work as expected. But for this unique case it's much easier and robust to do

$\exists!$\index[index]{$\exists"!$}
6
  • It's worked! Thank you very much!
    – Chau Long
    Commented Sep 25, 2023 at 11:27
  • However, the exclamation mark cannot work! \khm{$\exists$ !}. Is there any impact?
    – Chau Long
    Commented Sep 26, 2023 at 4:02
  • @ChauLong The exclamation mark is a special character for MakeIndex and must be quoted. Look in the manuals.
    – egreg
    Commented Sep 26, 2023 at 8:37
  • When I used \khm{$\exists$ !}, the PDF displayed properly but the index did not generate correctly. However, when I used escaped quote "! instead, \khm{$\exists$ "!}, the index worked but the PDF displayed the escaped characters ". It was difficult to get both the PDF display and the index generation working properly. Do you have any idea?
    – Chau Long
    Commented Sep 27, 2023 at 3:07
  • @ChauLong You can somewhat do that, but it's much simpler to do manually the indexing for that very special case. See edit.
    – egreg
    Commented Sep 27, 2023 at 8:36

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