Mathematics in Markdown
Overview
Mathematical equations and expressions written in LaTeX are common in academic and scientific publications. Your browser typically renders this mathematical markup using an open-source JavaScript display engine such as MathJax or KaTeX.
For example, with this LaTeX markup:
\[
\begin{aligned}
KL(\hat{y} || y) &= \sum_{c=1}^{M}\hat{y}_c \log{\frac{\hat{y}_c}{y_c}} \\
JS(\hat{y} || y) &= \frac{1}{2}(KL(y||\frac{y+\hat{y}}{2}) + KL(\hat{y}||\frac{y+\hat{y}}{2}))
\end{aligned}
\]
The MathJax display engine renders this:
Equations and expressions can be displayed inline with other text, or as standalone blocks. Block presentation is also known as “display” mode.
Whether an equation or expression appears inline, or as a block, depends on the delimiters that surround the mathematical markup. Delimiters are defined in pairs, where each pair consists of an opening and closing delimiter. The opening and closing delimiters may be the same, or different.
You can configure Hugo to render mathematical markup on the client side using the MathJax or KaTeX display engine, or you can render the markup with the
transform.ToMath function while building your site.
The first approach is described below.
Setup
Follow these instructions to include mathematical equations and expressions in your Markdown using LaTeX markup.
Step 1
Enable and configure the Goldmark passthrough extension in your site configuration. The passthrough extension preserves raw Markdown within delimited snippets of text, including the delimiters themselves.
markup:
goldmark:
extensions:
passthrough:
delimiters:
block:
- - \[
- \]
- - $$
- $$
inline:
- - \(
- \)
enable: true
params:
math: true
[markup]
[markup.goldmark]
[markup.goldmark.extensions]
[markup.goldmark.extensions.passthrough]
enable = true
[markup.goldmark.extensions.passthrough.delimiters]
block = [['\[', '\]'], ['$$', '$$']]
inline = [['\(', '\)']]
[params]
math = true
{
"markup": {
"goldmark": {
"extensions": {
"passthrough": {
"delimiters": {
"block": [
[
"\\[",
"\\]"
],
[
"$$",
"$$"
]
],
"inline": [
[
"\\(",
"\\)"
]
]
},
"enable": true
}
}
}
},
"params": {
"math": true
}
}
The configuration above enables mathematical rendering on every page unless you set the math parameter to false in front matter. To enable mathematical rendering as needed, set the math parameter to false in your site configuration, and set the math parameter to true in front matter. Use this parameter in your base template as shown in
Step 3.
The configuration above precludes the use of the $...$ delimiter pair for inline equations. Although you can add this delimiter pair to the configuration and JavaScript, you will need to double-escape the $ symbol when used outside of math contexts to avoid unintended formatting.
See the inline delimiters section for details.
To disable passthrough of inline snippets, omit the inline key from the configuration:
markup:
goldmark:
extensions:
passthrough:
delimiters:
block:
- - \[
- \]
- - $$
- $$
[markup]
[markup.goldmark]
[markup.goldmark.extensions]
[markup.goldmark.extensions.passthrough]
[markup.goldmark.extensions.passthrough.delimiters]
block = [['\[', '\]'], ['$$', '$$']]
{
"markup": {
"goldmark": {
"extensions": {
"passthrough": {
"delimiters": {
"block": [
[
"\\[",
"\\]"
],
[
"$$",
"$$"
]
]
}
}
}
}
}
}
You can define your own opening and closing delimiters, provided they match the delimiters that you set in Step 2.
markup:
goldmark:
extensions:
passthrough:
delimiters:
block:
- - '@@'
- '@@'
inline:
- - '@'
- '@'
[markup]
[markup.goldmark]
[markup.goldmark.extensions]
[markup.goldmark.extensions.passthrough]
[markup.goldmark.extensions.passthrough.delimiters]
block = [['@@', '@@']]
inline = [['@', '@']]
{
"markup": {
"goldmark": {
"extensions": {
"passthrough": {
"delimiters": {
"block": [
[
"@@",
"@@"
]
],
"inline": [
[
"@",
"@"
]
]
}
}
}
}
}
}
Step 2
Create a partial template to load MathJax or KaTeX. The example below loads MathJax, or you can use KaTeX as described in the engines section.
<script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js"></script>
<script>
MathJax = {
tex: {
displayMath: [['\\[', '\\]'], ['$$', '$$']], // block
inlineMath: [['\\(', '\\)']] // inline
},
loader:{
load: ['ui/safe']
},
};
</script>The delimiters above must match the delimiters in your site configuration.
Step 3
Conditionally call the partial template from the base template.
<head>
...
{{ if .Param "math" }}
{{ partialCached "math.html" . }}
{{ end }}
...
</head>The example above loads the partial template if you have set the math parameter in front matter to true. If you have not set the math parameter in front matter, the conditional statement falls back to the math parameter in your site configuration.
Step 4
Include mathematical equations and expressions in Markdown using LaTeX markup.
This is an inline \(a^*=x-b^*\) equation.
These are block equations:
\[a^*=x-b^*\]
\[ a^*=x-b^* \]
\[
a^*=x-b^*
\]
These are also block equations:
$$a^*=x-b^*$$
$$ a^*=x-b^* $$
$$
a^*=x-b^*
$$If you set the math parameter to false in your site configuration, you must set the math parameter to true in front matter. For example:
---
date: 2024-01-24T18:09:49-08:00
params:
math: true
title: Math examples
---+++
date = 2024-01-24T18:09:49-08:00
title = 'Math examples'
[params]
math = true
+++{
"date": "2024-01-24T18:09:49-08:00",
"params": {
"math": true
},
"title": "Math examples"
}
Inline delimiters
The configuration, JavaScript, and examples above use the \(...\) delimiter pair for inline equations. The $...$ delimiter pair is a common alternative, but using it may result in unintended formatting if you use the $ symbol outside of math contexts.
If you add the $...$ delimiter pair to your configuration and JavaScript, you must double-escape the $ when outside of math contexts, regardless of whether mathematical rendering is enabled on the page. For example:
A \\$5 bill _saved_ is a \\$5 bill _earned_.
If you use the $...$ delimiter pair for inline equations, and occasionally use the $ symbol outside of math contexts, you must use MathJax instead of KaTeX to avoid unintended formatting caused by
this KaTeX limitation.
Engines
MathJax and KaTeX are open-source JavaScript display engines. Both engines are fast, but at the time of this writing MathJax v3.2.2 is slightly faster than KaTeX v0.16.11.
If you use the $...$ delimiter pair for inline equations, and occasionally use the $ symbol outside of math contexts, you must use MathJax instead of KaTeX to avoid unintended formatting caused by
this KaTeX limitation.
See the inline delimiters section for details.
To use KaTeX instead of MathJax, replace the partial template from Step 2 with this:
<link
rel="stylesheet"
href="https://cdn.jsdelivr.net/npm/katex@0.16.21/dist/katex.min.css"
integrity="sha384-zh0CIslj+VczCZtlzBcjt5ppRcsAmDnRem7ESsYwWwg3m/OaJ2l4x7YBZl9Kxxib"
crossorigin="anonymous"
>
<script
defer
src="https://cdn.jsdelivr.net/npm/katex@0.16.21/dist/katex.min.js"
integrity="sha384-Rma6DA2IPUwhNxmrB/7S3Tno0YY7sFu9WSYMCuulLhIqYSGZ2gKCJWIqhBWqMQfh"
crossorigin="anonymous">
</script>
<script
defer
src="https://cdn.jsdelivr.net/npm/katex@0.16.21/dist/contrib/auto-render.min.js"
integrity="sha384-hCXGrW6PitJEwbkoStFjeJxv+fSOOQKOPbJxSfM6G5sWZjAyWhXiTIIAmQqnlLlh"
crossorigin="anonymous"
onload="renderMathInElement(document.body);">
</script>
<script>
document.addEventListener("DOMContentLoaded", function() {
renderMathInElement(document.body, {
delimiters: [
{left: '\\[', right: '\\]', display: true}, // block
{left: '$$', right: '$$', display: true}, // block
{left: '\\(', right: '\\)', display: false}, // inline
],
throwOnError : false
});
});
</script>The delimiters above must match the delimiters in your site configuration.
Chemistry
Both MathJax and KaTeX provide support for chemical equations. For example:
$$C_p[\ce{H2O(l)}] = \pu{75.3 J // mol K}$$
As shown in Step 2 above, MathJax supports chemical equations without additional configuration. To add chemistry support to KaTeX, enable the mhchem extension as described in the KaTeX documentation.