There are several possible approaches how to achieve this:
- configure TeX4ht to catch all math content and typeset it twice - once using MathML, second time as a verbatim text.
- parse MathML content and convert it back to the LaTeX code
- pre-process the input TeX file and modify it in the way it will be easier for working with
The first method could reuse the code that we use for the MathJax option in TeX4ht, see file mathjax-latex-4ht.4ht for details.
The second method won't produce the same LaTeX code as was the original input. It may be a problem for you. LuaXML can be used for the conversion.
I will present the third method in my answer. It consists of two components - the input filter that parses the input LaTeX file for the math content and marks it with some additional macros, and make4ht DOM filter that modifies the resulting HTML file to produce the correct MathML structure.
Here is the input filter. It reads input from the standard input and prints the modified output.
File altmath.lua:
-- insert envrionmnets that should be handled by the script here
local math_environments = {
equation = true,
displaymath = true,
["equation*"] = true,
}
-- macros that will be inserted to the updated document
local macros = [[
\NewDocumentCommand\inlinemath {mv} {\HCode{<span class="inlinemath">}#1\HCode{<span class="alt">}\NoFonts #2\EndNoFonts\HCode{</span></span>}}
\NewDocumentEnvironment{altdisplaymath}{} {\ifvmode\IgnorePar\fi\EndP\HCode{<div class="altmath">}} {\ifvmode\IgnorePar\fi\EndP\HCode{</div>}}
]]
-- we will insert macros before the second control sequence (we assume that first is \documentclass
local cs_counter = 0
-- we will hanlde inline and diplay math differently
local inline = 1
local display = 2
local function handle_math(input, nexts, stop, buffer, mathtype)
local content = input:sub(nexts, stop)
local format = "\inlinemath{%s}{%s}" -- format used to insert math content back to the doc
-- set format for display math
if mathtype == display then
format = [[
\begin{altdisplaymath}
%s
\begin{verbatim}
%s
\end{verbatim}
\end{altdisplaymath}
]]
end
buffer[#buffer + 1] = string.format(format, content, content )
end
local function find_next(input, start, buffer)
-- find next cs or math start
local nexts, stop = input:find("[$\]", start)
local mathtype
if nexts then
-- save current text chunk from the input buffer
buffer[#buffer+1] = input:sub(start, nexts - 1)
local kind, nextc = input:match("(.)(.)", nexts)
if kind == "\" then -- handle cs
-- insert our custom TeX macros before second control sequence
cs_counter = cs_counter + 1
if cs_counter == 2 then
buffer[#buffer+1] = macros
end
if nextc == "(" then -- inline math
_, stop = input:find("\)", nexts)
mathtype = inline
elseif nextc == "[" then -- display math
_, stop = input:find("\]", nexts)
mathtype = display
else -- maybe environment?
-- find environment name
local env_name = input:match("^begin%s{(.-)}", nexts+1)
-- it must be enabled as math environment
if env_name and math_environments[env_name] then
_, stop = input:find("\end%s{" .. env_name .. "}", nexts)
mathtype = display
else -- not math environment
buffer[#buffer+1] = "\" -- save backspace that was eaten by the processor
return stop + 1 -- return back to the main loop
end
end
else -- handle $
if nextc == "$" then -- display math
_, stop = input:find("%$%$", nexts + 1)
mathtype = display
else -- inline math
_, stop = input:find("%$", nexts + 1)
mathtype = inline
end
end
if not stop then -- something failed, move one char next
return nexts + 1
end
-- save math content to the buffer
handle_math(input, nexts, stop, buffer, mathtype)
else
-- if we cannot find any more cs or math, we need to insert rest of the input
-- to the output buffer
buffer[#buffer+1] = input:sub(start, string.len(input))
return nil
end
return stop + 1
end
-- process the input buffer, detect inline and display math and also math environments
local function process(input)
local buffer = {} -- buffer where text chunks are stored
local start = 1
start = find_next(input, start,buffer)
while start do
start = find_next(input, start, buffer)
end
return table.concat(buffer) -- convert output buffer to string
end
local content = io.read("*all")
print(process(content))
You can test it using the following command:
texlua altmath.lua < sample.tex
This is modified version of your original TeX file:
\documentclass{article}
\NewDocumentCommand\inlinemath {mv} {\HCode{<span class="inlinemath">}#1\HCode{<span class="alt">}\NoFonts #2\EndNoFonts\HCode{</span></span>}}
\NewDocumentEnvironment{altdisplaymath}{} {\ifvmode\IgnorePar\fi\EndP\HCode{<div class="altmath">}} {\ifvmode\IgnorePar\fi\EndP\HCode{</div>}}
\usepackage[T1]{fontenc}
\begin{document}
\title{Article Title Here}
\author{Author Name Here}
\maketitle
\section{Introduction}
This is the sample paragraph with \inlinemath{$a=b^2$}{$a=b^2$} inline math. Different \inlinemath{(a=c^2)}{(a=c^2)} type of math.
\begin{altdisplaymath}
\begin{equation}\label{eq1-11}
T,^{\prime}{\mu \nu} = \left( \frac{\partial \xi^\alpha} {\partial\xi^{\prime\mu}}\right) \left( \frac{\partial \xi^\beta}{\partial \xi^{\prime\nu}} \right) T{\alpha \beta}
\end{equation}
\begin{verbatim}
\begin{equation}\label{eq1-11}
T,^{\prime}{\mu \nu} = \left( \frac{\partial \xi^\alpha} {\partial\xi^{\prime\mu}}\right) \left( \frac{\partial \xi^\beta}{\partial \xi^{\prime\nu}} \right) T{\alpha \beta}
\end{equation}
\end{verbatim}
\end{altdisplaymath}
Please refer the equations \ref{eq1-11} for the further testing.
\end{document}
You can see that it inserts macro definitions after the \documentclass command. It defines the \inlinemath command and altdisplaymath environment. The definitions contain code that inserts HTML tags directly to the converted file. They are designed to be used just with TeX4ht.
You can convert your file to HTML using
texlua altmath.lua < sample.tex | make4ht -j sample - "mathml"
It produces a following code:
<span class='inlinemath'><!-- l. 14 --><math xmlns='http://www.w3.org/1998/Math/MathML' display='inline'><mi>a</mi> <mo class='MathClass-rel'>=</mo> <msup><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msup></math><span class='alt'>$a=b^2$</span></span>
or
<div class='altmath'> <!-- tex4ht:inline --><table class='equation'><tr><td>
<!-- l. 16 --><math xmlns='http://www.w3.org/1998/Math/MathML' display='block' class='equation'>
<mstyle class='label' id='x1-1001r1'></mstyle><!-- endlabel --><mi>T</mi><msubsup><mrow><mspace width='0.17em' class='thinspace'></mspace></mrow><mrow><mi mathvariant='italic'>μν</mi></mrow><mrow><mi>′</mi></mrow></msubsup> <mo class='MathClass-rel'>=</mo> <mrow><mo form='prefix' fence='true'> (</mo><mrow> <mfrac><mrow><mi>∂</mi><msup><mrow><mi>ξ</mi></mrow><mrow><mi>α</mi></mrow></msup></mrow>
<mrow><mi>∂</mi><msup><mrow><mi>ξ</mi></mrow><mrow><mi mathvariant='italic'>′μ</mi></mrow></msup></mrow></mfrac> </mrow><mo form='postfix' fence='true'>)</mo></mrow> <mrow><mo form='prefix' fence='true'> (</mo><mrow> <mfrac><mrow><mi>∂</mi><msup><mrow><mi>ξ</mi></mrow><mrow><mi>β</mi></mrow></msup></mrow>
<mrow><mi>∂</mi><msup><mrow><mi>ξ</mi></mrow><mrow><mi mathvariant='italic'>′ν</mi></mrow></msup></mrow></mfrac> </mrow><mo form='postfix' fence='true'>)</mo></mrow> <msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant='italic'>αβ</mi></mrow></msub>
</math></td><td class='eq-no'>(1)</td></tr></table>
<!-- l. 18 --><p class='nopar'>
</p>
<pre id='verbatim-1' class='verbatim'>
\begin{equation}\label{eq1-11}
T,^{\prime}{\mu \nu} = \left( \frac{\partial \xi^\alpha} {\partial\xi^{\prime\mu}}\right) \left( \frac{\partial \xi^\beta}{\partial \xi^{\prime\nu}} \right) T{\alpha \beta}
\end{equation}
</pre>
<!-- l. 23 --><p class='nopar'> </p></div>
We need to use make4ht DOM filter to create a correct MathML structure. Save the following file as build.lua:
local domfilter = require "make4ht-domfilter"
-- find mathml and insert TeX as an alternative annotation
local function update_mathml(element, class)
local alt_element_t = element:query_selector(class)
if not alt_element_t and not alt_element_t[1] then return nil end
-- save alt element contents and remove it from the document
local alt_contents = alt_element_t[1]:get_children()
alt_element_t[1]:remove_node()
-- create a new structure of the mathml element ->
-- mathml
-- semantics
-- mrow -> math content
-- annotation -> saved TeX
local mathml = element:query_selector("math")[1]
local mathml_contents = mathml:get_children()
local semantics = mathml:create_element("semantics")
local mrow = semantics:create_element("mrow")
mrow._children = mathml_contents -- this trick places saved original mathml content into a new <mrow>
semantics:add_child_node(mrow)
local annotation = semantics:create_element("annotation", {encoding="application/x-tex"})
annotation._children = alt_contents
semantics:add_child_node(annotation)
mathml._children = {semantics}
end
local process = domfilter {
function(dom)
for _, inline in ipairs(dom:query_selector(".inlinemath")) do
update_mathml(inline, ".alt")
end
for _, display in ipairs(dom:query_selector(".altmath")) do
update_mathml(display, ".verbatim")
end
return dom
end
}
It parses the HTML files for our custom <span> and <div> elements, get the alt text and inserts it as an '` element of the MathML code.
This is the result:
<h3 class='sectionHead'><span class='titlemark'>1 </span> <a id='x1-10001'></a>Introduction</h3>
<!-- l. 14 --><p class='noindent'>This is the sample paragraph with
<span class='inlinemath'><!-- l. 14 --><math display='inline' xmlns='http://www.w3.org/1998/Math/MathML'><semantics><mrow><mi>a</mi> <mo class='MathClass-rel'>=</mo> <msup><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow><annotation encoding='application/x-tex'>$a=b^2$</annotation></semantics></math></span> inline math.
Different <span class='inlinemath'><!-- l. 14 --><math display='inline' xmlns='http://www.w3.org/1998/Math/MathML'><semantics><mrow><mrow><mi>a</mi> <mo class='MathClass-rel'>=</mo> <msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></mrow><annotation encoding='application/x-tex'>\(a=c^2\)</annotation></semantics></math></span>
type of math. </p><div class='altmath'> <!-- tex4ht:inline --><table class='equation'><tr><td>
<!-- l. 16 --><math class='equation' xmlns='http://www.w3.org/1998/Math/MathML' display='block'><semantics><mrow>
<mstyle id='x1-1001r1' class='label'></mstyle><!-- endlabel --><mi>T</mi><msubsup><mrow><mspace width='0.17em' class='thinspace'></mspace></mrow><mrow><mi mathvariant='italic'>μν</mi></mrow><mrow><mi>′</mi></mrow></msubsup> <mo class='MathClass-rel'>=</mo> <mrow><mo fence='true' form='prefix'> (</mo><mrow> <mfrac><mrow><mi>∂</mi><msup><mrow><mi>ξ</mi></mrow><mrow><mi>α</mi></mrow></msup></mrow>
<mrow><mi>∂</mi><msup><mrow><mi>ξ</mi></mrow><mrow><mi mathvariant='italic'>′μ</mi></mrow></msup></mrow></mfrac> </mrow><mo fence='true' form='postfix'>)</mo></mrow> <mrow><mo fence='true' form='prefix'> (</mo><mrow> <mfrac><mrow><mi>∂</mi><msup><mrow><mi>ξ</mi></mrow><mrow><mi>β</mi></mrow></msup></mrow>
<mrow><mi>∂</mi><msup><mrow><mi>ξ</mi></mrow><mrow><mi mathvariant='italic'>′ν</mi></mrow></msup></mrow></mfrac> </mrow><mo fence='true' form='postfix'>)</mo></mrow> <msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant='italic'>αβ</mi></mrow></msub>
</mrow><annotation encoding='application/x-tex'>
\begin{equation}\label{eq1-11}
T\,^{\prime}_{\mu \nu} = \left( \frac{\partial \xi^\alpha} {\partial\xi^{\prime\mu}}\right) \left( \frac{\partial \xi^\beta}{\partial \xi^{\prime\nu}} \right) T_{\alpha \beta}
\end{equation}
</annotation></semantics></math></td><td class='eq-no'>(1)</td></tr></table>
<!-- l. 18 --><p class='nopar'>
</p>
<!-- l. 23 --><p class='nopar'> </p></div>
