TeX4ht: can we prevent italic capital greek letters in mathml or mathml,mathjax output

Question

I am trying to convert document to HTML with MathML rendered by MathJax (the reason is that pure mathjax output does not do proper equation numbering). Unfortunately, I get all the capital greek letters in formulas in italic font, while they clearly should be upright (as formatted by normal TeX).

That is, the test document

\documentclass{article}
\begin{document}
\[
  \Psi+\psi=P+p
\]
\end{document}

which is compiled with

make4ht -u test 'html,mathml,mathjax'

Gives the output that looks like

While I would clearly prefer the original LaTeX formatting

As for now, I can get the proper formula in two cases:

make4ht -u test 'html'

which inserts PNG image of the formula -- not at all what I would like to look nice on screen. Other way

make4ht -u test 'html,mathjax'

This one looks nice (proper resolution/browser independent formatting by MathJax), but fails on documents with equation numbering.

I would be glad to have suggestions!

Answer 1

You can try this .cfg file:

\Preamble{xhtml}
\begin{document}
\def\temp#1#2{\def#1{\PauseMathClass{\HCode{<mi mathvariant="normal">}\special{t4ht@+\string&{35}x#2{59}}x\HCode{</mi>}}\EndPauseMathClass}}
\temp\Psi{03A8}
\temp\Delta{0394}
\temp\Xi{039E}
\temp\Pi{03A0}
\temp\Sigma{03A3}
\temp\Upsilon{03A5}
\temp\Omega{03A9}
\EndPreamble

It redefines \Psi and other problematic programs to output <mi mathvariant="normal">Ψ</mi>. The mathvariant="normal" attribute is necessary in order to display Psi as upright text. TeX4ht produces by default just <mi> element, without this attribute. <mi> elements that contain just single letter are displayed in italics by MathML, so it is necessary to use the mathvariant attribute. The \special command uses TeX4ht DVI processing instructions to output Unicode codepoint of Psi. \PauseMathClass disables the normal TeX4ht font processing, we need this in order to prevent some additional tags be written.

This is the result: