Math

Write formulas in LaTeX between dollar signs. Clay typesets them with KaTeX when it builds the site, so pages show them right away, without JavaScript.

#Inline and on their own line

One dollar sign on each side puts a formula into the text:

The area of a circle is $A = \pi r^2$.

The area of a circle is $A=\pi r^{2}A\; =\; \backslash pi\; r^2$.

Two dollar signs on lines of their own set a formula apart, centered:

$$
\sum_{i=1}^{n} i = \frac{n(n+1)}{2}
$$

#More examples

$$
\begin{pmatrix} a & b \\ c & d \end{pmatrix}
\begin{pmatrix} x \\ y \end{pmatrix}
=
\begin{pmatrix} ax + by \\ cx + dy \end{pmatrix}
$$

$$
f(x) = \begin{cases} x^2 & \text{if } x \ge 0 \\ -x & \text{otherwise} \end{cases}
$$

KaTeX lists every command it knows in its documentation.

#Dollar signs in text

Prices stay text. A dollar sign only starts a formula when no space follows it, and only ends one when no space comes before it and no digit after it: “It costs $5 and $10” is text. To write a dollar sign that would start a formula, put a backslash before it: \$.

#Mistakes

A formula KaTeX cannot read is shown in red with its source, instead of failing the build, so you see it on the page: \frac{1.

#Accessibility and size

• Every formula is also written as MathML, which screen readers read out.
• Wide formulas scroll sideways on small screens instead of widening the page.
• The fonts for formulas only load on pages that have math.