% The trace of an operator.
\newcommand*{\trace}[1]{ \operatorname{trace}\of{{#1}} }
+
+% The "rank" of its argument, which is context-dependent. It can mean
+% any or all of,
+%
+% * the rank of a matrix,
+% * the rank of a power-associative algebra (particularly an EJA),
+% * the rank of an element in a Euclidean Jordan algebra.
+%
+\newcommand*{\rank}[1]{ \operatorname{rank}\of{{#1}} }
+
+
% The ``span of'' operator. The name \span is already taken.
\newcommand*{\spanof}[1]{ \operatorname{span}\of{{#1}} }