conversionmathmlxml
Is there a TeX engine that converts a TeX document to MathML or XML directly the way PDFTeX converts text input to PDF?
I am familiar with some converters that transform a subset of TeX into something that can be viewed on a browser, but they all leave out many of the packages I used, particularly hyperref and xypic. I want a converter that passes Knuth's test for genuine TeX.
The underlying solution is of course the same for ConTeXt and LaTeX: you need to have a way of changing what macros do such that they write the correct output rather than typesetting. This is also much the same as tex4ht does. The advantage ConTeXt has is that the macros are provided mainly by one focussed group, and they include the necessary 'back end' to make that conversion easy. To do the same for LaTeX, you need to handle all of the macros that might be present, which is a problem given the number and variety of LaTeX packages. So while in principal it's possible, the implementation is a severe challenge.
(With my 'LaTeX3 hat' on, this is an obvious area to bear in mind when defining an updated format. To do that, you need to have a much more 'regular' syntax and input than is often the case with LaTeX files at present. Again, I think ConTeXt shows how this can be done as it is already good on keeping the input within it's own structures.)
MathML is very verbose and is a pain to write manually, which is no problem if your code is automatically generated. For programs it is easy to parse, since it is XML.
TeX math code was designed to be written by humans and results in much shorter code. I cannot answer your question if one format will replace the other. As I mentioned they serve different purposes.
Is there any attempt to automatically transform one into the other that anyone is aware of?
I cannot speak for LaTeX, but in ConTeXt you can input MathML directly. Information about MathML in ConTeXt and the Wiki - MathML. Here is an example (credits to Hans Hagen) taken from one of the ConTeXt manuals:
\usemodule[mathml]
\starttext
\xmlprocessdata{}{
<?xml version="1.0" encoding="UTF-8"?>
<math xmlns="http://www.w3c.org/mathml" version="2.0">
<apply>
<eq/>
<apply>
<diff/>
<bvar>
<ci> x </ci>
</bvar>
<apply>
<root/>
<ci> u </ci>
</apply>
</apply>
<apply>
<times/>
<apply>
<divide/>
<cn> 1 </cn>
<apply>
<times/>
<cn> 2 </cn>
<apply>
<root/>
<ci> u </ci>
</apply>
</apply>
</apply>
<apply>
<diff/>
<bvar>
<ci> x </ci>
</bvar>
<ci> u </ci>
</apply>
</apply>
</apply>
</math>
}{}
\stoptext
The output:
For a TeX to MathML conversion, you can use the XML export, see ConTeXt wiki - epub and my answer to the question Converting ConTeXt document to HTML.
Best Answer
tex4htcan convert to XHTML and MathML. See my answer to this question.