Tex4ht 在 mathjax 模式下使用 dmath 时生成无效数学运算

Question

问题似乎在于位于&=... 内\left[。\right]这似乎是 MathJax 的问题。&字符应该用在内，align*以便正确对齐多行方程，但在这种情况下不起作用。也许我们可以省略它。

尝试这个版本的文件build：

local filter = require "make4ht-filter"

local function process_options(options)
  -- convert [number={foo}] to \tag{foo}
  local number = options:match("number%s*=%s*{?(%w+)")
  if number then
    return "\\tag{" .. number .. "}"
  end
  return ""
end


local function escape_equal(str)
  -- there can be multiple equal characters in the string. we should put the & character
  -- just before the one which is not inside any group
  -- escape nested equal signs
  str = str:gsub("({[^{^}]+)=([^{^}]+})", "%1:EQUAL:%2")
  -- replace remaining =
  str = str:gsub("=", "& =")
  -- return escaped =
  str = str:gsub(":EQUAL:", "=")
  return str
end

local function make_align(dgroup, new_env)
  -- change breqn environment contents to align*
  -- change = to &=
  
  local dgroup = dgroup
  if not new_env then
    dgroup = escape_equal(dgroup) --  <- we don't do this anymore, it leads only to problems
  end
  local new_env = new_env or  "\\begin{align*}\n%s\n\\end{align*}"
  -- return the fixed text in align* environment
  -- return "\\begin{".. new_env .."}" ..  dgroup .. "\\end{" .. new_env .. "}"
  return string.format(new_env, dgroup)
end

local function process_dgroup(s, env_name)
  return s:gsub("\\begin%s*{" .. env_name .. "}(.-)\\end%s*{" .. env_name .. "}",
  function(dgroup)
    -- remove environemnts
    -- change dmath[...,number={label}] to \tag{label}
    dgroup = dgroup:gsub("\\begin%s*{dmath}%s*(%b[])", process_options)
    -- remove all other environemnts
    dgroup = dgroup:gsub("\\begin%s*{.-}","")
    dgroup = dgroup:gsub("\\end%s*{.-}", "\\\\")
    return make_align(dgroup)
  end)
end

-- process remaining dmath environments
local function process_dmath(s, env_name, new_env)
  return s:gsub("\\begin%s*{" .. env_name .. "}(.-)\\end%s*{" .. env_name .. "}",
  function(dmath)
    -- options can be still here
    local dmath = dmath:gsub("^%s*(%b[])", process_options)
    return make_align(dmath, new_env)
  end)
end


local process = filter {
  -- find all dgroup* environments and convert them to align*
  function(s)
    local s = process_dgroup(s,"dgroup%*")
    s = process_dgroup(s, "dgroup")
    -- process remaining dmath environments in the document
    s = process_dmath(s, "dmath%*", "\\[\n%s\n\\]")
    s = process_dmath(s, "dmath", "\\begin{equation}\n%s\n \\end{equation}")
    return s
  end
}

-- install filter to match HTML files
Make:match("html?$", process)

变化是它现在不会将所有内容转换为环境align*，但它遵循breqn，所以dmath-> equation，和dmath*-> \[ ... \]。它也不会转义等号。

这是生成的 HTML：

<!-- l. 10 --><p class='noindent'>\[ \text {Solve}\left [3 \log (x)-\log \left (y(x) \sin \left (\frac {y(x)}{x^2}\right )+x^2 \cos \left (\frac {y(x)}{x^2}\right )\right )=c_1,y(x)\right ] \]
</p><!-- l. 14 --><p class='indent'>   \[
  \text {Solve}\left [3 \log (x)-\log \left (y(x) \sin \left (\frac {y(x)}{x^2}\right )+x^2 \cos \left (\frac {y(x)}{x^2}\right )\right )=c_1,y(x)\right ]  
\]
</p>

并由 MathJax 渲染：

Answer 1