-% The space of complex Hermitian n-by-n matrices.
-\newcommand*{\Hn}[1][n]{
- \mathcal{H}\if\detokenize{#1}\detokenize{1}{}\else^{#1}\fi
-}
-
+% 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}.
+\newcommand*{\Hn}[1][n]{ \mathcal{H}^{#1} }