New in 2.5.0: Allow reference numbers to be set in brackets (Issue #57).

New in 2.4.0: Updated to work with pandoc 2.11.

pandoc-eqnos 2.5.0

pandoc-eqnos is a pandoc filter for numbering equations and their references when converting markdown to other formats. It is part of the pandoc-xnos filter suite. LaTeX/pdf, html, and epub output have native support. Native support for docx output is a work in progress.

Demonstration: Processing demo3.md with pandoc + pandoc-eqnos gives numbered equations and references in pdf, tex, html, epub, docx and other formats (including beamer slideshows).

This version of pandoc-eqnos was tested using pandoc 1.15.2 - 2.11.1.1,¹ and may be used with linux, macOS, and Windows. Bug reports and feature requests may be posted on the project's Issues tracker. If you find pandoc-eqnos useful, then please kindly give it a star on GitHub.

Installation
Usage
Markdown Syntax
Customization
Technical Details
Getting Help
Development
What's New

Installation

Pandoc-eqnos requires python. It is easily installed -- see here.² Either python 2.7 or 3.x will do.

Pandoc-eqnos may be installed using the shell command

pip install pandoc-eqnos --user

and upgraded by appending --upgrade to the above command. Pip is a program that downloads and installs software from the Python Package Index, PyPI. It normally comes installed with a python distribution.³

Instructions for installing from source are given in DEVELOPERS.md.

Usage

Pandoc-eqnos is activated by using the

--filter pandoc-eqnos

option with pandoc. Alternatively, use

--filter pandoc-xnos

to activate all of the filters in the pandoc-xnos suite (if installed).

Any use of --filter pandoc-citeproc or --bibliography=FILE should come after the pandoc-eqnos or pandoc-xnos filter calls.

Markdown Syntax

The cross-referencing syntax used by pandoc-eqnos was developed in pandoc Issue #813 -- see this post by @scaramouche1.

To mark an equation for numbering, add an identifier to its attributes:

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

The prefix #eq: is required. id should be replaced with a unique string composed of letters, numbers, dashes and underscores. If id is omitted then the equation will be numbered but unreferenceable.

To reference the equation, use

@eq:id

{@eq:id}

Curly braces protect a reference and are stripped from the output.

Demonstration: Processing demo.md with pandoc + pandoc-eqnos gives numbered equations and references in pdf, tex, html, epub, docx and other formats.

Clever References

Writing markdown like

See eq. @eq:id.

seems a bit redundant. Pandoc-eqnos supports "clever references" via single-character modifiers in front of a reference. You can write

 See +@eq:id.

to have the reference name (i.e., "eq.") automatically generated. The above form is used mid-sentence; at the beginning of a sentence, use

 *@eq:id

instead. If clever references are enabled by default (see Customization, below), then users may disable it for a given reference using⁴

!@eq:id

Demonstration: Processing demo2.md with pandoc + pandoc-eqnos gives numbered equations and references in pdf, tex, html, epub, docx and other formats.

Note: When using *@eq:id and emphasis (e.g., *italics*) in the same sentence, the * in the clever reference must be backslash-escaped; i.e., \*@eq:id.

Tagged Equations

The equation number may be overridden by placing a tag in the equation's attributes block:

$$ y = mx + b $$ {#eq:id tag="B.1"}

The tag may be arbitrary text, or an inline equation such as $\mathrm{B.1'}$ . Mixtures of the two are not currently supported.

Disabling Links

To disable a link on a reference, set nolink=True in the reference's attributes:

@eq:id{nolink=True}

Customization

Pandoc-eqnos may be customized by setting variables in the metadata block or on the command line (using -M KEY=VAL). The following variables are supported:

eqnos-warning-level or xnos-warning-level - Set to 0 for no warnings, 1 for critical warnings, or 2 (default) for all warnings. Warning level 2 should be used when troubleshooting.
eqnos-cleveref or xnos-cleveref - Set to True to assume "+" clever references by default;
xnos-capitalise - Capitalises the names of "+" clever references (e.g., change from "fig." to "Fig.");
eqnos-plus-name - Sets the name of a "+" clever reference (e.g., change it from "eq." to "equation"). Settings here take precedence over xnos-capitalise;
eqnos-star-name - Sets the name of a "*" clever reference (e.g., change it from "Equation" to "Eq.");
eqnos-eqref - Set to True to use AMS-style equation references (i.e., equation numbers set in brackets); and
eqnos-number-by-section or xnos-number-by-section - Set to True to number equations by section (e.g., Eq. 1.1, 1.2, etc in Section 1, and Eq. 2.1, 2.2, etc in Section 2). For LaTeX/pdf, html, and epub output, this feature should be used together with pandoc's --number-sections option enabled. For docx, use docx custom styles instead.

This option should not be set for numbering by chapter in LaTeX/pdf book document classes.
xnos-number-offset - Set to an integer to offset the section numbers when numbering equations by section. For html and epub output, this feature should be used together with pandoc's --number-offset option set to the same integer value. For LaTeX/pdf, this option offsets the actual section numbers as required.
eqnos-default-env - Name of the default LaTeX environment (default: 'equation'). See Environments, below.

Note that variables beginning with eqnos- apply to only pandoc-eqnos, whereas variables beginning with xnos- apply to all of the pandoc-fignos/eqnos/tablenos/secnos.

Demonstration: Processing demo3.md with pandoc + pandoc-eqnos gives numbered equations and references in pdf, tex, html, epub, docx and other formats.

Environments

The default LaTeX environment may be overridden by adding an env attribute. For example:

$$ y = mx + b $$ {#eq:id env=multline}

The env attribute must be a valid amsmath environment. If the attribute value is of the form X.Y, X will be used as the name of the amsmath environment and Y will be used as an extra argument for the environment (e.g. the alignat environment expects an argument for the number of equation columns). This customization only affects LaTeX/PDF output only.

Technical Details

LaTeX/pdf Output

During processing, pandoc-eqnos inserts the packages and supporting LaTeX it needs into the header-includes metadata field. To see what is inserted, set the eqnos-warning-level meta variable to 2. Note that any use of pandoc's --include-in-header option overrides all header-includes.

An example reference in LaTeX looks like

See \cref{eq:polynomial}.

An example equation looks like

\begin{equation}
  y = \sum_{n=0}^{\infty} a_n x^n
  \label{eq:polynomial}
\end{equation}

Other details:

The cleveref package is used for clever references;
The \label and \ref macros are used for figure labels and references, respectively (\Cref and \cref are used for clever references);
Clever reference names are set with \Crefname and \crefname;
Tagged equations make use of the \tag macro;
If clever referencing is enabled, then AMS-style referencing is achieved by setting the \creflabelformat; otherwise, the amsmath \eqref macro is used.

Html/Epub Output

An example reference in html looks like

See eq. <a href="#eq:polynomial">1</a>.

An example equation looks like

<div id="eq:polynomial" class="eqnos" style="position: relative;
     width: 100%">
  <span class="math display">
    y = \sum_{n=0}^{\infty} a_n x^n
  </span>
  <span style="position: absolute; right: 0em; top: 50%;
        line-height:0; text-align: right">
    (1)
  </span>
</div>

The equation and its number are wrapped in a <div></div> with an id for linking and with class eqnos to allow for css styling. The number is in a separate span from the equation and is positioned right.

Docx Output

Docx OOXML output is under development and subject to change. Native capabilities will be used wherever possible.

Getting Help

If you have any difficulties with pandoc-eqnos, or would like to see a new feature, then please submit a report to our Issues tracker.

Development

Pandoc-eqnos will continue to support pandoc 1.15-onward and python 2 & 3 for the foreseeable future. The reasons for this are that a) some users cannot upgrade pandoc and/or python; and b) supporting all versions tends to make pandoc-eqnos more robust.

Developer notes are maintained in DEVELOPERS.md.

What's New

New in 2.5.0: Allow reference numbers to be set in brackets (Issue #57).

New in 2.4.0: Updated to work with pandoc 2.11.

New in 2.3.0: Allow LaTeX equation environment customization (Pull Request #44).

New in 2.2.3: Fixed XHTML Transitional validation error (Issue #50).

New in 2.2.1: Updated for pandoc 2.10.1.

New in 2.1.1: Warnings are now given for duplicate reference targets.

New in 2.0.0: This version represents a major revision of pandoc-eqnos. While the interface is similar to that of the 1.x series, some users may encounter minor compatibility issues.

Warning messages are a new feature of pandoc-eqnos. The meta variable eqnos-warning-level may be set to 0, 1, or 2 depending on the degree of warnings desired. Warning level 1 will alert users to bad references, malformed attributes, and unknown meta variables. Warning level 2 (the default) adds informational messages that should be helpful with debugging. Level 0 turns all messages off.

Meta variable names have been updated. Deprecated names have been removed, and new variables have been added. Note in particular that the eqnos-number-sections and xnos-number-sections variables have been renamed to eqnos-number-by-section and xnos-number-by-section, respectively.

The basic filter and library codes have been refactored and improved with a view toward maintainability. While extensive tests have been performed, some problems may have slipped through unnoticed. Bug reports should be submitted to our Issues tracker.

LaTeX/PDF:

LaTeX codes produced by pandoc-eqnos are massively improved. The hacks used before were causing some users problems. The new approach provides more flexibility and better compatibility with the LaTeX system.

Supporting LaTeX is now written to the header-includes meta data. Users no longer need to include LaTeX commands in the header-includes to get basic pandoc-eqnos functions to work. Use eqnos-warning-level: 2 to see what pandoc-eqnos adds to the header-includes.

A word of warning: Pandoc-eqnos's additions to the header-includes are overridden when pandoc's --include-in-header option is used. This is owing to a design choice in pandoc. Users may choose to deliberately override pandoc-eqnos's header-includes by providing their own LaTeX through --include-in-header. If a user needs to include other bits of LaTeX in this way, then they will need to do the same for the LaTeX that pandoc-eqnos needs.

Html/Epub:

The equation is now enclosed in a <div> which contains the id and class eqnos. This change was made to facilitate styling, and for consistency with pandoc-fignos and pandoc-tablenos. An inline-block <span> was formerly used instead.

Epub support is generally improved.

Footnotes

1: Pandoc 2.4 broke how references are parsed, and so is not supported.

2: For MacOS, my preferred install method is to use the package available from python.org.

3: Anaconda users may be tempted to use conda instead. This is not advised. The packages distributed on the Anaconda cloud are unofficial, are not posted by me, and in some cases are ancient. Some tips on using pip in a conda environment may be found here.

4: The disabling modifier "!" is used instead of "-" because pandoc drops minus signs in front of references.

tomduck/pandoc-eqnos