}
\fi
+% The reduced row-echelon form of its argument, a matrix.
+\newcommand*{\rref}[1]{\operatorname{rref}\of{#1}}
+\ifdefined\newglossaryentry
+ \newglossaryentry{rref}{
+ name={\ensuremath{\rref{A}}},
+ description={the reduced row-echelon form of $A$},
+ sort=r
+ }
+\fi
+
% The ``Automorphism group of'' operator.
\newcommand*{\Aut}[1]{ \operatorname{Aut}\of{{#1}} }
% The space of complex Hermitian n-by-n matrices. Does not reduce to
% merely "H" when n=1 since H^{n} does not mean an n-fold cartesian
-% product of H^{1}.
+% product of H^{1}. The field may also be given rather than assumed
+% to be complex; for example \Hn[3]\of{\mathbb{O}} might denote the
+% 3-by-3 Hermitian matrices with octonion entries.
\newcommand*{\Hn}[1][n]{ \mathcal{H}^{#1} }
\ifdefined\newglossaryentry
\newglossaryentry{Hn}{