Formula

{$ \varphi=\frac{1+\sqrt{5}}{2} $}

Summary: Lightweight rendering of mathematical formulas in wiki pages

Version: 2026-01-07

Prerequisites: ExtensionHub

Status: Beta

Maintainer: Petko

Users: +1 (view / edit)

Discussion: Formula-Talk

License: MIT (Formula), Apache (MathJax)

A very lightweight rendering of mathematical formulas in wiki pages (using MathJax locally).

Description

This is a simple, small and lightweight recipe for displaying mathematical formulas in PmWiki pages. Authors write in the wiki page the TeX code of the formula inside a {$ ... $} block. The formula is rendered to a picture by a local copy of the MathJax SVG library.

Note, Google killed the Charts API, so the recipe now uses MathJax and was rewritten to the new Extensions format. See Notes.

The solutions of the equation {$ ax^2+bx+c=0 $} can be found with

{$ x_{1,2}=\frac{-b \pm \sqrt {b^2-4ac}}{2a} $}

The solutions of the equation {$ ax^2+bx+c=0 $} can be found with

{$ x_{1,2}=\frac{-b\pm\sqrt{b^2-4ac}}{2a} $}

Installation

If you have installed the old Formula recipe, please remove it from config.php.

This extension requires ExtensionHub.

Place Formula-2026-01-07.zip in the pmwiki/extensions directory on your server. Optionally you can unzip it.

Alternatively, you can clone the Git repo into pmwiki/extensions with such a command line:
git clone --depth=1 https://github.com/5ko/Formula.git

Configuration

To enable the extension, navigate to SiteAdmin.ExtensionHub, locate the "Formula" row and press "Edit". On the new page, check the checkbox "Enable configuration" and near the bottom press "Save".

Usage

Just write the TeX code of the formula inside a {$ ... $} block:

Golden ratio

{$ \varphi = \frac{1 + \sqrt{5}}{2} \simeq 1,618034 $}

Golden ratio

{$ \varphi=\frac{1+\sqrt{5}}{2}\simeq 1,618034 $}

How many solutions this equation has? (9th grade Algebra class)

{$ 2 = \frac{(3-x) \times 2}{3-x} $}

How many solutions this equation has? (9th grade Algebra class)

{$ 2=\frac{(3-x)\times 2}{3-x} $}

Maximum allowed deformation of a concrete beam under charge (1st year Architecture class)

{$ f_{max} = {L \over \beta } = { M_{max} \times L^2 \over \alpha \times E \times I } \
= { ( q \times L^2 ) \times L^2 \times 12 \over 2 \times \mu^2 \times \alpha \times E \times b \times h^3 } $}

Maximum allowed deformation of a concrete beam under charge (1st year Architecture class)

{$ f_{max}={L\over\beta}={M_{max}\times L^2\over\alpha\times E\times I}={(q\times L^2)\times L^2\times 12\over 2\times\mu^2\times\alpha\times E\times b\times h^3} $}

You can find more information about TeX at Wikipedia:TeX.

It is possible to set the text and background colors of individual formulas, wrap these in WikiStyles:

Here is a red formula %red% {$ e^x=\lim_{n\to\infty}\(1+\frac xn\)^n $} %%

Text and background: %green bgcolor=#eef% {$ (a+b)^2=a^2+2ab+b^2 $} %%

Background only: %bgcolor=#fbb% {$ \sum_{i=1}^ni=\frac{n(n+1)}2 $} %%

Here is a red formula {$ e^x=\lim_{n\to\infty}(1+\frac xn)^n $}

Text and background: {$ (a+b)^2=a^2+2ab+b^2 $}

Background only: {$ \sum_{i=1}^ni=\frac{n(n+1)}2 $}

Notes

There may be slight differences between the current MathJax library and the previous Google Charts service.
- So far it seems that parentheses no longer need to be escaped with backslashes.
- A \hspace or \vspace markup needs to have the dimension in units like \vspace{9mm} rather than \vspace9.
- There may be more.
Versions before 2026-01-07 embedded pictures, and the text and background colors needed to be written inside the formula and be passed to the API. Now you can simply use WikiStyles.
The new version adapts to the container font size, so you can have formulas in headings or again wrap them in WikiStyles with bigger or smaller fonts:

# %font-size=.7em% {$ ax^2+bx+c $} Smaller
# {$ ax^2+bx+c $} Normal size
# %font-size=1.2em% {$ ax^2+bx+c $} Bigger

{$ ax^2+bx+c $} Smaller
{$ ax^2+bx+c $} Normal size
{$ ax^2+bx+c $} Bigger

The answer to the Algebra question is, "An infinite number of solutions: x can be any number, except 3."

Change log / Release notes

2026-01-07 - Google has disabled the Chart API, so I rewrote this to be an extension using MathJax locally.
If you previously used Formula, please disable it before installing the extension.
20220104 - Update for Cookbook:PmSyntax and Cookbook:CustomSyntax (2+spaces).
20211229 - Update for Cookbook:PmSyntax.
20211217a - Highlight some additional control characters in the formula.
20211217 - Minor simplification of the highlighting rules.
20211216 - Update for Cookbook:PmSyntax compatibility with highlighted attributes, special strings and meta.
20211215 - Update for Cookbook:PmSyntax compatibility.
20211214 - Change deprecated curly brackets in lines 50 - 54 (warning in PHP 7.4, Siegfried Seibert)
20180420 - Fixes for PHP 7.2.
20150405 - Fixes for PHP 5.5.
20111029a - Fixed bugs with special characters, added per-formula colors.
20111027 - Initial public release, ready to be tested.

Contributors

Extension written and maintained by Petko (5ko [snail] 5ko [period] fr).
The old/classic recipe formula.php file was partly based on the MimeTex recipe, copyright 2004-2007 Patrick R. Michaud.
If this recipe helps you or saves you time, you can help support its continued development by ♥ .

Comments

See discussion at Formula-Talk

User notes +1: If you use, used or reviewed this recipe, you can add your name. These statistics appear in the Cookbook listings and will help newcomers browsing through the wiki.