domain, then the preimage under $f$ of $A$ is $\preimage{f}{A}$.
\end{section}
+ \begin{section}{Calculus}
+ The gradient of $f : \Rn \rightarrow \Rn[1]$ is $\gradient{f} :
+ \Rn \rightarrow \Rn$.
+ \end{section}
+
\begin{section}{Common}
The function $f$ applied to $x$ is $f\of{x}$. We can group terms
like $a + \qty{b - c}$ or $a + \qty{b - \sqty{c - d}}$. Here's a
The conic hull of a set $X$ is $\cone{X}$; its affine hull is
$\aff{X}$, and its convex hull is $\conv{X}$. If $K$ is a cone,
then its lineality space is $\linspace{K}$, its lineality is
- $\lin{K}$, and its extreme directions are $\Ext{K}$.
+ $\lin{K}$, and its extreme directions are $\Ext{K}$. The fact that
+ $F$ is a face of $K$ is denoted by $F \faceof K$; if $F$ is a
+ proper face, then we write $F \properfaceof K$.
\end{section}
\begin{section}{Font}