Kramdown Math Syntax

Linux_DebugNotes_04

Keypoints

• Kramdown in Jekyll
• MathJax
• How to write math formula in kramdown

Kramdown in Jekyll

• Kramdown is a Markdown-superset converter
• Jekyll uses Kramdown as its default Markdown engine

MathJax

• MathJax is a JavaScript display engine for mathematics that works in all browsers.
• Kramdown supports MathJax, but it doesn’t include MathJax by default.

How to write math formula in kramdown

• To fix Kramdown doesn’t support $$ as inline mathmatics, add the following code in _includes/head.html:

    <!-- Mathjax Support -->
    <script>
    MathJax = {
    tex: {
        inlineMath: [['$', '$'], ['\\(', '\\)']]
        }
    };
    </script>
    <script id="MathJax-script" async
        src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js">
    </script>
  

  • inlineMath is used to define the inline math delimiter. It is to enable $$ can be used in kramdown for inline mathmatical formula.

  • Math syntax in kramdown: the default math delimiters are $$...$$ and \[...\] for displayed mathematics, and \(...\) for in-line mathematics.

• To fix matrix registers new lines issue:This is caused by rendering \\ as \ by default in markdown parser. And \ is an escape character commonly used across many programming languages. You could use a \ before every actual \ you want to use. So if you wanted \begin{bmatrix} you would have to write \\begin{bmatrix} and if you want \\ you need to use \\\\.
  • Example:

      $ \\begin{bmatrix}a & b \\\\ c & d\\end{bmatrix} $
    

• To avoid

  in $$ part. But use \vert !!!

• Example:

    $$
    \\begin{align*}
    & \phi(x,y) = \phi \left(\sum_{i=1}^n x_ie_i, \sum_{j=1}^n y_je_j \right)
    = \sum_{i=1}^n \sum_{j=1}^n x_i y_j \phi(e_i, e_j) = \\
    & (x_1, \ldots, x_n) \left( \\begin{array}{ccc}
        \phi(e_1, e_1) & \cdots & \phi(e_1, e_n) \\
        \vdots & \ddots & \vdots \\
        \phi(e_n, e_1) & \cdots & \phi(e_n, e_n)
        \end{array} \right)
    \left( \\begin{array}{c}
        y_1 \\
        \vdots \\
        y_n
        \end{array} \right)
    \end{align*}
    $$
  

  • The above code will be rendered as: \(\\begin{align*} & \phi(x,y) = \phi \left(\sum_{i=1}^n x_ie_i, \sum_{j=1}^n y_je_j \right) = \sum_{i=1}^n \sum_{j=1}^n x_i y_j \phi(e_i, e_j) = \\ & (x_1, \ldots, x_n) \left( \\begin{array}{ccc} \phi(e_1, e_1) & \cdots & \phi(e_1, e_n) \\ \vdots & \ddots & \vdots \\ \phi(e_n, e_1) & \cdots & \phi(e_n, e_n) \end{array} \right) \left( \\begin{array}{c} y_1 \\ \vdots \\ y_n \end{array} \right) \end{align*}\)

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