Run this with `cargo test --features gen-tests suite::math`.
# Math
Mathematical expressions following the remark-math convention.
Inline math uses `$...$`, display math uses `$$` fences on separate lines.
## Inline math
Basic inline math:
```````````````````````````````` example
$x=y$
.
<p><code class="language-math math-inline">x=y</code></p>
````````````````````````````````
Inline math with LaTeX:
```````````````````````````````` example
$\sqrt{3x-1}+(1+x)^2$
.
<p><code class="language-math math-inline">\sqrt{3x-1}+(1+x)^2</code></p>
````````````````````````````````
Inline math without surrounding whitespace:
```````````````````````````````` example
foo$1+1 = 2$bar
.
<p>foo<code class="language-math math-inline">1+1 = 2</code>bar</p>
````````````````````````````````
Multiple inline math expressions:
```````````````````````````````` example
$a$ and $b$
.
<p><code class="language-math math-inline">a</code> and <code class="language-math math-inline">b</code></p>
````````````````````````````````
Adjacent inline math:
```````````````````````````````` example
$a$$b$
.
<p><code class="language-math math-inline">a$$b</code></p>
````````````````````````````````
Multiline inline math:
```````````````````````````````` example
$5x + 2 =
17$
.
<p><code class="language-math math-inline">5x + 2 =
17</code></p>
````````````````````````````````
Double dollar signs inline produce inline math:
```````````````````````````````` example
$$\alpha$$
.
<p><code class="language-math math-inline">\alpha</code></p>
````````````````````````````````
Math content ignores HTML:
```````````````````````````````` example
$a<b>c</b>$
.
<p><code class="language-math math-inline">a<b>c</b></code></p>
````````````````````````````````
Math content ignores backticks:
```````````````````````````````` example
$not `code`$
.
<p><code class="language-math math-inline">not `code`</code></p>
````````````````````````````````
Math content ignores markdown links:
```````````````````````````````` example
$$
.
<p><code class="language-math math-inline"></code></p>
````````````````````````````````
Math content ignores autolinks:
```````````````````````````````` example
$<https://not.a.link/>$
.
<p><code class="language-math math-inline"><https://not.a.link/></code></p>
````````````````````````````````
Math content ignores entities:
```````````````````````````````` example
$α$
.
<p><code class="language-math math-inline">&alpha;</code></p>
````````````````````````````````
Inline math cannot start with whitespace:
```````````````````````````````` example
$ y=x$
.
<p><code class="language-math math-inline"> y=x</code></p>
````````````````````````````````
Inline math cannot end with whitespace:
```````````````````````````````` example
$y=x $
.
<p><code class="language-math math-inline">y=x </code></p>
````````````````````````````````
Unclosed dollar signs are plain text:
```````````````````````````````` example
Hello $world.
.
<p>Hello $world.</p>
````````````````````````````````
Dollar at end of line:
```````````````````````````````` example
Dollar at end of line$
.
<p>Dollar at end of line$</p>
````````````````````````````````
Escaped dollar in math:
```````````````````````````````` example
$\$$
.
<p>$$$</p>
````````````````````````````````
Backslashes in math:
```````````````````````````````` example
$\{a\,b\}$
.
<p><code class="language-math math-inline">\{a\,b\}</code></p>
````````````````````````````````
Inline math in emphasis:
```````````````````````````````` example
_$a$ equals $b$_
.
<p><em><code class="language-math math-inline">a</code> equals <code class="language-math math-inline">b</code></em></p>
````````````````````````````````
Inline math in strong:
```````````````````````````````` example
**$a$ equals $b$**
.
<p><strong><code class="language-math math-inline">a</code> equals <code class="language-math math-inline">b</code></strong></p>
````````````````````````````````
Inline math preceded by text:
```````````````````````````````` example
a$x$
.
<p>a<code class="language-math math-inline">x</code></p>
````````````````````````````````
Math as only item on a line:
```````````````````````````````` example
$x=y$
.
<p><code class="language-math math-inline">x=y</code></p>
````````````````````````````````
Text following inline math:
```````````````````````````````` example
$n$-th order
.
<p><code class="language-math math-inline">n</code>-th order</p>
````````````````````````````````
Math with angle brackets:
```````````````````````````````` example
$a <b > c$
.
<p><code class="language-math math-inline">a <b > c</code></p>
````````````````````````````````
Math with markdown-like content:
```````````````````````````````` example
$[(a+b)c](d+e)$
.
<p><code class="language-math math-inline">[(a+b)c](d+e)</code></p>
````````````````````````````````
Math with underscores:
```````````````````````````````` example
${a}_b c_{d}$
.
<p><code class="language-math math-inline">{a}_b c_{d}</code></p>
````````````````````````````````
Currency amounts are not math:
```````````````````````````````` example
Thus, $20,000 and USD$30,000 won't parse
.
<p>Thus, <code class="language-math math-inline">20,000 and USD</code>30,000 won't parse</p>
````````````````````````````````
Whitespace after opening dollar prevents math:
```````````````````````````````` example
It is 2$ for a can of soda, not 1$.
.
<p>It is 2<code class="language-math math-inline"> for a can of soda, not 1</code>.</p>
````````````````````````````````
Whitespace before closing dollar prevents math:
```````````````````````````````` example
I'll give $20 today, if you give me more $ tomorrow.
.
<p>I'll give <code class="language-math math-inline">20 today, if you give me more </code> tomorrow.</p>
````````````````````````````````
Escaped dollars inside math:
```````````````````````````````` example
Money adds: $\$X + \$Y = \$Z$.
.
<p>Money adds: <code class="language-math math-inline">\</code>X + $Y = $Z$.</p>
````````````````````````````````
Hard breaks not recognized in math:
```````````````````````````````` example
$not a\
hard break
either$
.
<p><code class="language-math math-inline">not a\
hard break
either</code></p>
````````````````````````````````
Inline math with escaped closing dollar:
```````````````````````````````` example
$\alpha\$
.
<p><code class="language-math math-inline">\alpha\</code></p>
````````````````````````````````
## Precedence and greedy parsing
Inline math vs code span — math first:
```````````````````````````````` example
$Inline `first$ then` code
.
<p><code class="language-math math-inline">Inline `first</code> then` code</p>
````````````````````````````````
Inline math vs code span — code first:
```````````````````````````````` example
`Code $first` then$ inline
.
<p><code>Code $first</code> then$ inline</p>
````````````````````````````````
Display math vs code span — math first:
```````````````````````````````` example
$$ Display `first $$ then` code
.
<p><code class="language-math math-inline">Display `first</code> then` code</p>
````````````````````````````````
Display math vs code span — code first:
```````````````````````````````` example
`Code $$ first` then $$ display
.
<p><code>Code $$ first</code> then $$ display</p>
````````````````````````````````
Empty inline math not allowed:
```````````````````````````````` example
Oops empty $$ expression.
.
<p>Oops empty $$ expression.</p>
````````````````````````````````
Greedy left-to-right dollar parsing:
```````````````````````````````` example
$x$$$$$$$y$$
.
<p>$x$$$$$$$y$$</p>
````````````````````````````````
Greedy left-to-right dollar parsing 2:
```````````````````````````````` example
$x$$$$$$y$$
.
<p>$x$$$$$$y$$</p>
````````````````````````````````
Greedy left-to-right dollar parsing 3:
```````````````````````````````` example
$$x$$$$$$y$$
.
<p><code class="language-math math-inline">x$$$$$$y</code></p>
````````````````````````````````
Alpha then double dollar:
```````````````````````````````` example
alpha$$beta$gamma$$delta
.
<p>alpha<code class="language-math math-inline">beta$gamma</code>delta</p>
````````````````````````````````
## Block structure interactions
Block structure takes precedence — list interrupts math:
```````````````````````````````` example
$x + y - z$
$x + y
- z$
$$ x + y
> z $$
.
<p><code class="language-math math-inline">x + y - z</code></p>
<p>$x + y</p>
<ul>
<li>z$</li>
</ul>
<pre><code class="language-math math-display">> z $$</code></pre>
````````````````````````````````
Empty lines start new paragraph, breaking math:
```````````````````````````````` example
$not
math$
$$
not
math
$$
.
<p>$not</p>
<p>math$</p>
<pre><code class="language-math math-display">not
math</code></pre>
````````````````````````````````
Nested list structure breaks math:
```````````````````````````````` example
- $not
- *
math$
.
<ul>
<li>$not
<ul>
<li>*
math$</li>
</ul>
</li>
</ul>
````````````````````````````````
## Display math
Basic display math:
```````````````````````````````` example
$$
\beta+\gamma
$$
.
<pre><code class="language-math math-display">\beta+\gamma</code></pre>
````````````````````````````````
Display math after paragraph:
```````````````````````````````` example
**Bold**
$$
x = y
$$
.
<p><strong>Bold</strong></p>
<pre><code class="language-math math-display">x = y</code></pre>
````````````````````````````````
Display math with meta string:
```````````````````````````````` example
$$ meta
x
$$
.
<pre><code class="language-math math-display">x</code></pre>
````````````````````````````````
Empty display math:
```````````````````````````````` example
$$
$$
.
<pre><code class="language-math math-display"></code></pre>
````````````````````````````````
Multiple display math blocks:
```````````````````````````````` example
$$
a
$$
$$
b
$$
.
<pre><code class="language-math math-display">a</code></pre>
<pre><code class="language-math math-display">b</code></pre>
````````````````````````````````
Triple dollar fence:
```````````````````````````````` example
$$$
alpha
$$$
.
<pre><code class="language-math math-display">alpha</code></pre>
````````````````````````````````
Indented display math (up to 3 spaces):
```````````````````````````````` example
$$
x
$$
.
<pre><code class="language-math math-display">x</code></pre>
````````````````````````````````
4-space indentation becomes code block:
```````````````````````````````` example
$$
x
$$
.
<pre><code>$$
x
$$
</code></pre>
````````````````````````````````
Unterminated display math at end of document:
```````````````````````````````` example
$$
unterminated
.
<pre><code class="language-math math-display">unterminated</code></pre>
````````````````````````````````
Display math in list items:
```````````````````````````````` example
- $a$
- $$
b
$$
.
<ul>
<li><code class="language-math math-inline">a</code></li>
<li>
<pre><code class="language-math math-display">b</code></pre>
</li>
</ul>
````````````````````````````````
Display math interrupts paragraph:
```````````````````````````````` example
tango
$$
\alpha
$$
.
<p>tango</p>
<pre><code class="language-math math-display">\alpha</code></pre>
````````````````````````````````
Spacing before closing fence:
```````````````````````````````` example
$$
\alpha
$$
.
<pre><code class="language-math math-display">\alpha</code></pre>
````````````````````````````````
Spacing after closing fence:
```````````````````````````````` example
$$
\alpha
$$
.
<pre><code class="language-math math-display">\alpha</code></pre>
````````````````````````````````
Display math with blank lines in content:
```````````````````````````````` example
$$
1
+ 1
= 2
$$
.
<pre><code class="language-math math-display">
1
+ 1
= 2
</code></pre>
````````````````````````````````
Escaped delimiters are not math fences:
```````````````````````````````` example
Foo \$1$ bar
\$\$
1
\$\$
.
<p>Foo $1$ bar</p>
<p>$$
1
$$</p>
````````````````````````````````
Display math with Cauchy-Schwarz:
```````````````````````````````` example
**The Cauchy-Schwarz Inequality**
$$
\left( \sum_{k=1}^n a_k b_k \right)^2 \leq \left( \sum_{k=1}^n a_k^2 \right) \left( \sum_{k=1}^n b_k^2 \right)
$$
.
<p><strong>The Cauchy-Schwarz Inequality</strong></p>
<pre><code class="language-math math-display">\left( \sum_{k=1}^n a_k b_k \right)^2 \leq \left( \sum_{k=1}^n a_k^2 \right) \left( \sum_{k=1}^n b_k^2 \right)</code></pre>
````````````````````````````````
Display and inline in same list:
```````````````````````````````` example
- $a$
$$
a
$$
- $$
b
$$
.
<ul>
<li>
<p><code class="language-math math-inline">a</code></p>
<pre><code class="language-math math-display">a</code></pre>
</li>
<li>
<pre><code class="language-math math-display">b</code></pre>
</li>
</ul>
````````````````````````````````
Display math in blockquote:
```````````````````````````````` example
> $$
> x
> $$
.
<blockquote>
<pre><code class="language-math math-display">x</code></pre>
</blockquote>
````````````````````````````````
Dollar in display text block:
```````````````````````````````` example
$$
\text{$b$}
$$
.
<pre><code class="language-math math-display">\text{$b$}</code></pre>
````````````````````````````````
Dollar-math with spaces on same line:
```````````````````````````````` example
When $a \ne 0$, there are two solutions to $(ax^2 + bx + c = 0)$ and they are
$$ x = {-b \pm \sqrt{b^2-4ac} \over 2a} $$
.
<p>When <code class="language-math math-inline">a \ne 0</code>, there are two solutions to <code class="language-math math-inline">(ax^2 + bx + c = 0)</code> and they are
<code class="language-math math-inline">x = {-b \pm \sqrt{b^2-4ac} \over 2a}</code></p>
````````````````````````````````
## Math in context
Math in link:
```````````````````````````````` example
[$a$](x)
.
<p><a href="x"><code class="language-math math-inline">a</code></a></p>
````````````````````````````````
Math preceded by various characters:
```````````````````````````````` example
$\pi$
'$\pi$
"$\pi$
($\pi$
[$\pi$
{$\pi$
/$\pi$
.
<p><code class="language-math math-inline">\pi</code>
'<code class="language-math math-inline">\pi</code>
"<code class="language-math math-inline">\pi</code>
(<code class="language-math math-inline">\pi</code>
[<code class="language-math math-inline">\pi</code>
{<code class="language-math math-inline">\pi</code>
/<code class="language-math math-inline">\pi</code></p>
````````````````````````````````
Inline math in italic text:
```````````````````````````````` example
_Equation $\Omega(69)$ in italic text_
.
<p><em>Equation <code class="language-math math-inline">\Omega(69)</code> in italic text</em></p>
````````````````````````````````
Inline math wrapped in quotes:
```````````````````````````````` example
$x$ $`y`$
.
<p><code class="language-math math-inline">x</code> <code class="language-math math-inline">`y`</code></p>
````````````````````````````````
Math vs HTML mix-up:
```````````````````````````````` example
$a <b > c$
$[(a+b)c](d+e)$
${a}_b c_{d}$
.
<p><code class="language-math math-inline">a <b > c</code></p>
<p><code class="language-math math-inline">[(a+b)c](d+e)</code></p>
<p><code class="language-math math-inline">{a}_b c_{d}</code></p>
````````````````````````````````
Spacing around dollar sign in math mode:
```````````````````````````````` example
$x = \$$
.
<p>$x = $$</p>
````````````````````````````````
Math starting with negative sign:
```````````````````````````````` example
foo$-1+1 = 2$bar
.
<p>foo<code class="language-math math-inline">-1+1 = 2</code>bar</p>
````````````````````````````````
Images and math in same list:
```````````````````````````````` example
- 
- $x$
.
<ul>
<li><img src="https://nodejs.org/static/images/logo.svg" alt="node logo"></li>
<li><code class="language-math math-inline">x</code></li>
</ul>
````````````````````````````````