Re: Texinfo TeX accepts LaTeX math, how?

[Patrice Dumas]

On Mon, Oct 26, 2020 at 04:45:21PM +0000, Gavin Smith wrote:
> On Mon, Oct 26, 2020 at 11:58:56AM +0100, Patrice Dumas wrote:
> > Hello,
> > 
> > Surprisingly (for me), the @displaymath example in the Texinfo manual
> > works when producing a pdf using texi2dvi.  However, it uses \frac{}{},
> > which is not not a plain TeX construct, as far as I know.  How is that
> > possible?  If the math in Texinfo is "LaTeX math" it is much simpler for
> > writers, as "plain TeX math" is less known that "LaTeX math" but also
> > for math rendering in HTML, as it means that latex2html can be used
> > without trouble and htlatex can be used instead of httex.
> 
> I added \frac to texinfo.tex very recently as it is easy to implement
> and probably the most missed LaTeX command by far.  However, it could
> be confusing to use in the manual as it wouldn't get over that plain
> TeX should be used.

Ok!  Mystery solved :-).

> > If it is not the same as LaTeX math, but a superset of plain TeX math,
> > could you tell me how I can modify the TeX file produced by tex4ht.pm
> > for httex such that there is support of the same constructs in math
> > rendering through tex4ht?  Right now, \frac appears as undefined when
> > processing with httex.
> 
> In that case it would be simpler just to use \over in the example.

Ok, that's what I did for the tests.

> Another option is to use htlatex instead (if there is such a program),
> but that could be problematic if there are any important usages of
> plain TeX that don't work with LaTeX.

I have no idea on that.  It is not clear to me to what extent LaTeX is a
superset of TeX or something different.  If it is a superset, indeed,
LaTeX tools could always be used, which could be simpler in some cases.

-- 
Pat