title: How to use MathJax in Slidify?
body: <p>It seems that all that need to do is to claim <code>widget: mathjax</code> in the title page. But I can't get the formulas correctly rendered. Anything missing? Thank you.</p>
  
  <p><img src="https://i.stack.imgur.com/Tqk47.png" alt="enter image description here"></p>
  
  <p><strong>UPDATE</strong>: I checked the final <code>index.html</code>, and found that many "*"'s have become <code>&lt;em&gt;</code> or <code>&lt;/em&gt;</code>.
  It seems that slidify is mixing the <code>*</code> in LaTeX and the <code>*</code> in markdown.</p>
  
  <p>Here is my LaTeX snippet:</p>
  
  <pre><code>\begin{align*}
  &amp;\begin{bmatrix}
  \mathbf{y}\\
  y_*
  \end{bmatrix}
  =\mathcal{N}\left(0,\begin{bmatrix}
  K &amp; K_*\\
  K_*^T &amp; K_{**}
  \end{bmatrix}\right)\\
  \Longrightarrow &amp; y_*|\mathbf{y}\sim\mathcal{N}\left(K_*K^{-1}\mathbf{y},K_{**}-K_*K^{-1}K_*^T\right)\\
  \Longrightarrow &amp; \overline{y_*}=K_*K^{-1}\mathbf{y}
  \end{align*}
  </code></pre>
  
  <p>which is converted to</p>
  
  <pre><code>&lt;li&gt;Inference
  $$\begin{align&lt;em&gt;}
  &amp;amp;\begin{bmatrix}
  \mathbf{y}\
  y_&lt;/em&gt;
  \end{bmatrix}
  =\mathcal{N}\left(0,\begin{bmatrix}
  K &amp;amp; K&lt;em&gt;*\
  K&lt;/em&gt;&lt;em&gt;^T &amp;amp; K_{&lt;/em&gt;&lt;em&gt;}
  \end{bmatrix}\right)\
  \Longrightarrow &amp;amp; y_&lt;/em&gt;|\mathbf{y}\sim\mathcal{N}\left(K&lt;em&gt;*K^{-1}\mathbf{y},K&lt;/em&gt;{*&lt;em&gt;}-K&lt;em&gt;*K^{-1}K&lt;/em&gt;&lt;/em&gt;^T\right)\
  \Longrightarrow &amp;amp; \overline{y&lt;em&gt;*}=K&lt;/em&gt;&lt;em&gt;K^{-1}\mathbf{y}
  \end{align&lt;/em&gt;}$$&lt;/li&gt;
  &lt;/ul&gt;
  </code></pre>
  
  <p><strong>UPDATE 2</strong>: I substituted the <code>&amp;#95;</code> for <code>_</code> and <code>&amp;#42;</code> for <code>*</code>, as well as <code>\\</code> for some <code>\</code>. And it looks quite good now:</p>
  
  <pre><code>$$\\begin{align&amp;#42;}
  &amp;\\begin{bmatrix}
  \mathbf{y}\\\\
  y&amp;#95;&amp;#42;
  \\end{bmatrix}
  =\mathcal{N}\left(0,\begin{bmatrix}
  K &amp; K&amp;#95;&amp;#42;\\\\
  K&amp;#95;&amp;#42;^T &amp; K&amp;#95;{&amp;#42;&amp;#42;}
  \\end{bmatrix}\right)\\\\
  \Longrightarrow &amp; y&amp;#95;&amp;#42;\big|\mathbf{y}\sim\mathcal{N}\left(K&amp;#95;&amp;#42;K^{-1}\mathbf{y},K&amp;#95;{&amp;#42;&amp;#42;}-K&amp;#95;&amp;#42;K^{-1}K&amp;#95;&amp;#42;^T\right)\\\\
  \Longrightarrow &amp; \bar{y}&amp;#95;&amp;#42;=K&amp;#95;&amp;#42;K^{-1}\mathbf{y}
  \\end{align&amp;#42;}$$
  </code></pre>