Math support in Sphinx

New in version 0.5.

Since mathematical notation isn’t natively supported by HTML in any way, Sphinx supports math in documentation with two extensions.

The basic math support that is common to both extensions is contained in sphinx.ext.mathbase. Other math support extensions should, if possible, reuse that support too.

Note

mathbase is not meant to be added to the extensions config value, instead, use either sphinx.ext.pngmath or sphinx.ext.jsmath as described below.

The input language for mathematics is LaTeX markup. This is the de-facto standard for plain-text math notation and has the added advantage that no further translation is necessary when building LaTeX output.

mathbase defines these new markup elements:

:math:

Role for inline math. Use like this:

Since Pythagoras, we know that :math:`a^2 + b^2 = c^2`.

.. math::

Directive for displayed math (math that takes the whole line for itself).

The directive supports multiple equations, which should be separated by a blank line:

.. math::

   (a + b)^2 = a^2 + 2ab + b^2

   (a - b)^2 = a^2 - 2ab + b^2

In addition, each single equation is set within a split environment, which means that you can have multiple aligned lines in an equation, aligned at & and separated by \\:

.. math::

   (a + b)^2  &=  (a + b)(a + b) \\
              &=  a^2 + 2ab + b^2

For more details, look into the documentation of the AmSMath LaTeX package.

When the math is only one line of text, it can also be given as a directive argument:

.. math:: (a + b)^2 = a^2 + 2ab + b^2

Normally, equations are not numbered. If you want your equation to get a number, use the label option. When given, it selects a label for the equation, by which it can be cross-referenced, and causes an equation number to be issued. See eqref for an example. The numbering style depends on the output format.

There is also an option nowrap that prevents any wrapping of the given math in a math environment. When you give this option, you must make sure yourself that the math is properly set up. For example:

.. math::
   :nowrap:

   \begin{eqnarray}
      y    & = & ax^2 + bx + c \\
      f(x) & = & x^2 + 2xy + y^2
   \end{eqnarray}

:eq:

Role for cross-referencing equations via their label. This currently works only within the same document. Example:

.. math:: e^{i\pi} + 1 = 0
   :label: euler

Euler's identity, equation :eq:`euler`, was elected one of the most
beautiful mathematical formulas.

sphinx.ext.pngmath – Render math as PNG images

This extension renders math via LaTeX and dvipng into PNG images. This of course means that the computer where the docs are built must have both programs available.

There are various config values you can set to influence how the images are built:

pngmath_latex

The command name with which to invoke LaTeX. The default is 'latex'; you may need to set this to a full path if latex is not in the executable search path.

Since this setting is not portable from system to system, it is normally not useful to set it in conf.py; rather, giving it on the sphinx-build command line via the -D option should be preferable, like this:

sphinx-build -b html -D pngmath_latex=C:\tex\latex.exe . _build/html

Changed in version 0.5.1: This value should only contain the path to the latex executable, not further arguments; use pngmath_latex_args for that purpose.

pngmath_dvipng

The command name with which to invoke dvipng. The default is 'dvipng'; you may need to set this to a full path if dvipng is not in the executable search path.

pngmath_latex_args

Additional arguments to give to latex, as a list. The default is an empty list.

New in version 0.5.1.

pngmath_latex_preamble

Additional LaTeX code to put into the preamble of the short LaTeX files that are used to translate the math snippets. This is empty by default. Use it e.g. to add more packages whose commands you want to use in the math.

pngmath_dvipng_args

Additional arguments to give to dvipng, as a list. The default value is ['-gamma 1.5', '-D 110'] which makes the image a bit darker and larger then it is by default.

An arguments you might want to add here is e.g. '-bg Transparent', which produces PNGs with a transparent background. This is not enabled by default because some Internet Explorer versions don’t like transparent PNGs.

Note

When you “add” an argument, you need to reproduce the default arguments if you want to keep them; that is, like this:

pngmath_dvipng_args = ['-gamma 1.5', '-D 110', '-bg Transparent']

pngmath_use_preview

dvipng has the ability to determine the “depth” of the rendered text: for example, when typesetting a fraction inline, the baseline of surrounding text should not be flush with the bottom of the image, rather the image should extend a bit below the baseline. This is what TeX calls “depth”. When this is enabled, the images put into the HTML document will get a vertical-align style that correctly aligns the baselines.

Unfortunately, this only works when the preview-latex package is installed. Therefore, the default for this option is False.

sphinx.ext.jsmath – Render math via JavaScript

This extension puts math as-is into the HTML files. The JavaScript package jsMath is then loaded and transforms the LaTeX markup to readable math live in the browser.

Because jsMath (and the necessary fonts) is very large, it is not included in Sphinx. You must install it yourself, and give Sphinx its path in this config value:

jsmath_path

The path to the JavaScript file to include in the HTML files in order to load JSMath. There is no default.

The path can be absolute or relative; if it is relative, it is relative to the _static directory of the built docs.

For example, if you put JSMath into the static path of the Sphinx docs, this value would be jsMath/easy/load.js. If you host more than one Sphinx documentation set on one server, it is advisable to install jsMath in a shared location.