Re: MathJax support in texi2any

[Gavin Smith]

On Tue, Oct 13, 2020 at 01:40:44AM +0200, Patrice Dumas wrote:
> @display already means something unrelated to math, I would suggest not
> using it especially.
> 
> > In fact, an alternative is to detect when there is input like
> > 
> > @tex
> > $$a+b$$
> > @end tex
> > 
> > and process this as display math.
> 
> That's exactly what I proposed to avoid...

It would also be incompatible with documents that already used this
syntax and provided other options for other output formats - the block
would be output twice.

> Indeed, instead of using a
> format specifc command, specific environements like
> 
> @displaymath
> a+b
> @end displaymath
> 
> @equation
> a+b
> @end equation
> 
> could be used.

I like @displaymath better, as an equation would have to have an equals sign.

> Actually, it is not perfect, as the language used for
> the math in those @-command could be LaTeX or TeX, or something else, 
> for example MathML, as there is nothing like a Texinfo math language.

There is the same issue with the existing command @math.  I say just leave
it as plain TeX and worry about AMS-LaTex another time.

> > DocBook has the <equation> element which could be used for DocBook
> > output (https://tdg.docbook.org/tdg/4.5/equation.html).
> 
> Indeed, but only if there is something similar in Texinfo, and also
> what is inside should be expanded to a format thta can be nested in 
> <equation>.  Looks like using an image would probably be the best in
> that case.

I see, so you wouldn't want TeX syntax in the DocBook output.

> > > Another remark, I think that the class that enables mathjax should be
> > > specific and not 'math', as we may want, for example to have the math
> > > class be added to @math element irrespective of mathjax being handled
> > > or not.  For example, tex2jax_process could be used to be similar with 
> > > tex2jax_ignore.
> > 
> > So <em class='math'> by default, and
> > <em class='math' class='tex2jax_process'> for MathJax?
> 
> I would favor no class by default and class='tex2jax_process' for MathJax.
> I think that we should avoid using class='math' unless there is a need,
> such as a specific css style.  Or we shold start doing that for all the
> @-commmands consistently.

I think <em class='math'> marks it as math and this would allow it to be
processed by some other tool.  Just using <em> would give no way to find
the unprocessed TeX code in the file.

> Also I may be wrong, but it seems that <em class='math' 
> class='tex2jax_process'>
> would not be correct, it should be
> <em class='math tex2jax_process'>
> Which means that it would probably be better to call _attribute_class
> if both a class for css that can be inlined and another class, such as 
> tex2jax_process is needed, by adding, for example an array argument to
> _attribute_class to pass additional classes not corresponding to css
> style, and also maybe handling the case of the $class argument set to
> undef.  No need to do anything until there is a concrete case, though.

I see.  I only used <em class='tex2jax_process'> for HTML_MATH=mathjax
so that should be OK.