3

This might be an known limitation in tex4ht, I do not know. But this MWE below gives the error

! Package amsmath Error: \tag not allowed here.

Only when run with make4ht. No error with lualatex nor with pdflatex.

\documentclass[11pt]{article}
\usepackage{amsmath} 

\begin{document}
\[
x=y \tag{1}
\]
\end{document}

The output is

>make4ht  foo.tex
.....
LaTeX2e <2017/01/01> patch level 3
Babel <3.9r> and hyphenation patterns for 83 language(s) loaded.
(./foo.tex (/usr/local/texlive/2016/texmf-dist/tex/latex/base/article.cls
Document Class: article 2014/09/29 v1.4h Standard LaTeX document class
(/usr/local/texlive/2016/texmf-dist/tex/latex/base/size11.clo))
....
(/usr/local/texlive/2016/texmf-dist/tex/generic/tex4ht/html4.4ht)
(/usr/local/texlive/2016/texmf-dist/tex/generic/tex4ht/html4-math.4ht))
(/usr/local/texlive/2016/texmf-dist/tex/generic/tex4ht/html4.4ht)
(/usr/local/texlive/2016/texmf-dist/tex/generic/tex4ht/html4-math.4ht))
(./foo.aux)

! Package amsmath Error: \tag not allowed here.

See the amsmath package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                                                                                    
l.7 x=y \tag
            {1}
?

List files

*File List*
 article.cls    2014/09/29 v1.4h Standard LaTeX document class
  size11.clo    2014/09/29 v1.4h Standard LaTeX file (size option)
 amsmath.sty    2016/11/05 v2.16a AMS math features
 amstext.sty    2000/06/29 v2.01 AMS text
  amsgen.sty    1999/11/30 v2.0 generic functions
  amsbsy.sty    1999/11/29 v1.2d Bold Symbols
  amsopn.sty    2016/03/08 v2.02 operator names

Version

which make4ht
/usr/local/texlive/2016/texmf-dist/scripts/make4ht/make4ht

Is the above known issue with make4ht? What should I do to workaround this? Do I need to change \[..\] to \begin{align}....\end{align} to use \tag{} with tex4ht? No error there with make4ht. Only error when using tag with \[..\]

Improve this question
3
  • 3
    Generally, \[...\] used for the unnumbered display equation, may be the error due to that tag, as you suggested, change the same to align environment then check the same...
    – MadyYuvi
    Jul 25 '17 at 9:53
  • 1
    @MadyYuvi -- please not align! single-line equations should use the equation environment. (the spacing above and below is calculated differently for equation and align.)
    – barbara beeton
    Jul 25 '17 at 14:36
  • @MadyYuvi But for one equation I've always used \[...\] and not align. Also there is no error with lualatex nor with pdflatex using tag with \[...\]. I've also seen tag used with \[...\] by Latex experts. For example this accepted answer adding-letters-to-equation-numbers uses tag with \[...\]
    – Nasser
    Jul 25 '17 at 18:10
1

Amsmath rededines \[ and \] to produce \begin{equation*} resp. \end{equation*}. tex4ht redefines it to something different, so the \tag doesn't work here anymore. You can try the amsmath definitions yourself:

\Preamble{xhtml}

\DeclareRobustCommand{\[}{\begin{equation*}}
\DeclareRobustCommand{\]}{\end{equation*}}
\begin{document}
\EndPreamble

This is a result:

enter image description here

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2
  • 1
    Why don't we update the amsmath.sty in tex4ht to include these \DeclareRobustCommand's?
    – Yai0Phah
    Jan 24 '19 at 19:02
  • @FrankScience I cannot get it to work correctly, it clashes with some options
    – michal.h21
    Jan 24 '19 at 20:05

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