Pandoc: How can I get numbered LaTeX equations to show up in both PDF and HTML output

Question

To make a numbered equation in Pandoc, I defer to using pure LaTeX:

\begin{equation}
a^2 + b^2 = c^2
\end{equation}

In PDF form, it gives a nice numbered equation, however, this equation doesn't show up at all in the HTML output because the equation is within the \begin environment and is ignored. I would like to keep the numbering in the PDF, but would like the equation to show up in the HTML, with or without the numbering.

Answer 1

An extension exists on github: pandoc-crossref

install it with

cabal update
cabal install pandoc-crossref

or in archlinux using ArchHaskell

pacman -Sy pandoc-crossref

you can use it by doing

$$ math $$ {#eq:label}
[@eq:label]

and compiling with

pandoc file.md --filter pandoc-crossref -o file.pdf

for more information see the documentation

Alternatively, as described in https://github.com/jgm/pandoc/issues/1938#issuecomment-74011358 you can use --mathjax for HTML rendering

if your equations are in math.txt

$$ a^2 + b^2 = c^2 $$

create a file header

<script type="text/x-mathjax-config">
  MathJax.Hub.Config({ TeX: { equationNumbers: {autoNumber: "all"} } });
</script>

and compile with

pandoc math.txt -t html -s -o test.html --mathjax=https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML -H header 

Answer 2

In pandoc you can do:

(@foo)  $a^2 + b^2 = c^2$

As (@foo) says, ...

(@bar)  $e = x + y$

This will give you running equation numbers in both PDF and HTML. However, the equations will not be centered or display-formatted. (You can use $$ for display math, but then the numbers probably won't be lined up right -- though maybe this can be fixed with CSS.)

Answer 3

Another option for equation numbers and references is the pandoc-eqnos filter.

Install pandoc-eqnos as root using the bash command

pip install pandoc-eqnos 

To tag an equation with the label eq:description, use

$$ y = mx + b $$ {#eq:description}

The prefix #eq: is required whereas description can be replaced with any combination of letters, numbers, dashes, slashes and underscores.

To reference the equation, use

@eq:description

To apply the filter, use the following option with pandoc:

--filter pandoc-eqnos

Full details and demos are given on the pandoc-eqnos Web page at github.

Answer 4

If you use css styling you can add the following in your css file:

/*create an equation counter variable */

body {
   counter-reset:  EQU_COUNT 0 ;
}

and:

.MathJax_Display:after {
      content: "      (" counter(EQU_COUNT) ")";    
      counter-increment: EQU_COUNT;           
    }

This will automatically add a an incremented counter value after each equation.

Answer 5

Using math2svg & CSS

The math2svg Lua filter for Pandoc converts LaTeX math to MathJax generated scalable vector graphics (SVG) for insertion into the output document in a standalone manner. SVG output is in any of the available MathJax fonts.

This is useful when a CSS paged media engine (such as Prince XML) cannot process complex JavaScript as required by MathJax. See: https://www.print-css.rocks for information about CSS paged media, a W3C standard.

Below example CSS code centers display math whilst adding equation numbers to the right.

span.math.display {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    }

span.math.display svg {
    margin: 0 auto;
    max-width: 85%;
    }

span.math.display:after {
    counter-increment: equation;
    content: '(' counter(equation) ')';
    font-weight: bold;
    }

More in-depth information is available from the math2svg documentation.

Using ConTeXt

If ConTeXt is used as the engine to produce the PDF output, then one can simply precede the LaTeX display formula with a \placeformula ConTeXt command in the Pandoc Markdown input:

\placeformula
$$ a^2 + b^2 = c^2 $$

When multiple output formats are desired, it is better to use a GNU makefile containing a sed command:

SHELL := /usr/bin/env bash
NAME := $(basename $(wildcard *.md))

all: $(NAME).pdf $(NAME).docx

$(NAME).pdf: $(NAME).md
    pandoc \
    <(sed 's/^$$$$.*/\\placeformula\n&/' $<) \
    --smart --output=$(NAME).tex --to=context
    context $(NAME).tex

$(NAME).docx: $(NAME).md
    pandoc $< --smart --output=$(NAME).docx

Answer 6

Another alternative is to render the equations as PDF minipages, convert to SVG, and display those on the Web.