Re: behavior of @math with HTML output

[Jacob Bachmeyer]

Gavin Smith wrote:
> On Fri, Oct 14, 2022 at 09:27:22PM -0500, Jacob Bachmeyer wrote:
>   
> > TeX has an \ifmmode conditional that is true in math mode; @var/\var and
> > other marking macros could be adjusted to mark their arguments appropriately
> > when invoked in math mode.  Are there other macros that would be appropriate
> > in @math?  At first glance, @var seems unique here.
> >     
>
> It's a good question.  I understand why someone would want to use @var
> inside @math, for consistent appearance of variables.
>
> It already appears to work well with texinfo.tex, with
>
>   @math{@var{foo}\over @var{bar}} finds the quotient of @var{foo} by
>   @var{bar}.  @math{\sqrt{@var{radicand}}} finds the square root of
>   @var{radicand}. 
>
> producing good results (even using the smaller font for foo and bar).
>   

Since @math is defined to use TeX syntax in its argument, would it be 
better to extend the other Texinfo processors to recognize \var inside 
@math and do whatever is needed to make it act as @var in that case?

The manual could add:

   Because math expressions will often contain variables also mentioned
   in running text, Texinfo supports one extension to plain TeX in
   @math:  the Texinfo @var{...} command is available as \var{...}
   inside the argument of a @math command.

... or something similar.  There is no (good) way to make this /not/ 
work with texinfo.tex (for TeXnical reasons) but the other Texinfo 
processors would need to be extended to support it.

> It also works well enough with MathJax with Patrice's latest change,
> using \mathit for the variable names (there appears to be no "\mathsl" so
> there is a slight difference in font style in and out of math - this
> seems unavoidable).

If I am reading my copy of /TeX for the Impatient/ correctly, the 
ordinary plain TeX \sl command should work in math mode.  Note that I am 
not sure that HTML normally has slanted fonts at all, so MathJax may be 
stuck with substituting italics for slanted; this would be an output 
format limitation, much as plain text and Info lack the ability to 
change fonts at all, but should also be consistent:  if HTML substitutes 
italics for slanted, the normal use of @var would also produce italic text.


-- Jacob