makeindex and fourier's mathbb

Question

In the example document below the second index entry produces the warning

!! Input index error (file = j.idx, line = 2):
   -- Extra `@' at position 11 of first argument.

on running makeglossaries corresponding to

\indexentry{A@\( \mathbb A \)}{1}
\indexentry{R@\( \math@bb  R \)}{1}
\indexentry{B@\( B \)}{1}

in the .idx file. As a result the second entry is rejected and does not appear in the .ind file or index.

As the first entry shows, a work around is to move the \index command outside of \emph. But swapping the fourier package for amssymb demonstrates that it is not necessary in general.

Is there a way to modify the behaviour of the fourier package so such index entries work inside \emph?

\documentclass{article}

\usepackage{fourier}
%\usepackage{amssymb}

\usepackage{makeidx}
\makeindex

\begin{document}

The \index{A@\( \mathbb A \)}%
\emph{\index{R@\( \mathbb R \)}%
\index{B@\( B \)}real numbers \( \mathbb R \)}.

\printindex
\end{document}

score 2 · Accepted Answer · edited Jul 12 '15 at 12:35

For some reasons, fourier.sty doesn't do

\DeclareSymbolFontAlphabet{\mathbb}{Ufutm}

but

\DeclareSymbolFontAlphabet{\math@bb}{Ufutm}
\AtBeginDocument{%
  \let\mathbb\math@bb
  [...<code omitted>...]
}

so the first level expansion of \mathbb becomes \protect\math@bb and the latter macro name gets written in the .idx file.

Workaround:

\documentclass{article}

\usepackage{fourier}

\makeatletter
\AtBeginDocument{\protected\def\mathbb{\math@bb}}
\makeatother

\usepackage{makeidx}
\makeindex

\begin{document}

The \index{A@\( \mathbb{A} \)}%
\emph{\index{R@\( \mathbb{R} \)}%
\index{B@\( B \)}real numbers \( \mathbb{R} \)}.

\printindex
\end{document}

This is the .idx file

\indexentry{A@\( \mathbb{A} \)}{1}
\indexentry{R@\( \mathbb {R} \)}{1}
\indexentry{B@\( B \)}{1}

Note, however, that you as usual risk different entries for those \index commands that are inside arguments to macros.

Avoid it, if you can. Otherwise do

\newcommand{\asindex}[1]{\index{#1}}

or add \string in front of the control sequences in the argument to \index when the command is in the argument to another one.

Many thanks. The preamble command works well. How would one use the \string approach in this case? — Andrew Swann, Jul 12 '15 at 12:39

score 1 · Answer 2 · answered Jul 12 '15 at 12:05

1

You can use

\emph{\index{R@\( \protect\mathbb R \)}%

Normally \index is read verbatim, but that does not work inside the argument of another command.

answered Jul 12 '15 at 12:05

David Carlisle

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makeindex and fourier's mathbb

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