Embedding equations in GitHub blog posts with MathJax
One of the first things I wanted to do for this blog was to be able to write equations as in LaTeX. I thought this would be straightforward, but it took some searching to find a better solution than embedding images of the equations generated by an external tool. The simple answer is: use MathJax that has a syntax almost identical to LaTeX. More recent GitHub themes (I forked Jekyll Now) already have kramdown enabled in the _config.yml file, supporting MathJax.
The steps are then the following:
1) If you want to use equations in your blog posts as I do, paste the following script into post.html that should be in your layouts folder
<script type="text/javascript" src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
<script>
MathJax.Hub.Config({
config: ["MMLorHTML.js"],
extensions: ["tex2jax.js","TeX/AMSmath.js","TeX/AMSsymbols.js"],
jax: ["input/TeX"],
tex2jax: {
inlineMath: [ ['$','$'], ["\\(","\\)"] ],
displayMath: [ ['$$','$$'], ["\\[","\\]"] ],
processEscapes: false
},
TeX: {
TagSide: "right",
TagIndent: ".8em",
MultLineWidth: "85%",
equationNumbers: {
autoNumber: "AMS",
},
unicode: {
fonts: "STIXGeneral,'Arial Unicode MS'"
}
},
showProcessingMessages: false
});
</script>
within the block:
{ % if page.mathjax % }
(code comes here)
{ % endif % }
This means that you can set up a mathjax flag for those posts where you’ll have equations.
2) In the posts where you’ll have equations insert the flag
mathjax: true
3) You can now write equations between double $ signs. For example,
\begin{bmatrix} X_1\\ X_2\\ \end{bmatrix} = \begin{bmatrix} a_{11} & a_{12}\\ 0 & 0\\ \end{bmatrix} \begin{bmatrix} X_1\\ X_2\\ \end{bmatrix}
+ \begin{bmatrix} 0\\ h_2\\ \end{bmatrix} \begin{bmatrix} l_1 & l_2 \end{bmatrix} \begin{bmatrix} X_1\\ X_2\\ \end{bmatrix}
+ \begin{bmatrix} da\\ dh + C_k \end{bmatrix}
becomes
\[\begin{bmatrix} X_1\\ X_2\\ \end{bmatrix} = \begin{bmatrix} a_{11} & a_{12}\\ 0 & 0\\ \end{bmatrix} \begin{bmatrix} X_1\\ X_2\\ \end{bmatrix} + \begin{bmatrix} 0\\ h_2\\ \end{bmatrix} \begin{bmatrix} l_1 & l_2 \end{bmatrix} \begin{bmatrix} X_1\\ X_2\\ \end{bmatrix} + \begin{bmatrix} da\\ dh + C_k \end{bmatrix}\]A good resource for different formulae is here.
tools github-blog