Support TeX and LaTeX math delimiters (#243)

_includes/js-selector.html

@@ -23,8 +23,25 @@
 
 {% if page.math %}
   <!-- MathJax -->
-  <script defer src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script>
-  <script defer src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script>
+  <script>
+  // see: <https://docs.mathjax.org/en/latest/options/input/tex.html#tex-options>
+  MathJax = {
+    tex: {
+      inlineMath: [              // start/end delimiter pairs for in-line math
+        ['$','$'],
+        ['\\(','\\)']
+      ],
+      displayMath: [             // start/end delimiter pairs for display math
+        ['$$', '$$'],
+        ['\\[', '\\]']
+      ]
+    }
+  };
+  </script>
+  <script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script>
+  <script type="text/javascript" id="MathJax-script" async
+    src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js">
+  </script>
 {% endif %}
 
 {% if jekyll.environment == 'production' %}

_posts/2019-08-08-text-and-typography.md

@@ -147,7 +147,7 @@ The mathematics powered by [**MathJax**](https://www.mathjax.org/):
 
 $$ \sum_{n=1}^\infty 1/n^2 = \frac{\pi^2}{6} $$
 
-When \\(a \ne 0\\), there are two solutions to \\(ax^2 + bx + c = 0\\) and they are
+When $a \ne 0$, there are two solutions to $ax^2 + bx + c = 0$ and they are
 
 $$ x = {-b \pm \sqrt{b^2-4ac} \over 2a} $$