\newcommand*{\Lnplus}[1][n]{ \mathcal{L}^{{#1}}_{+} }
% The PSD cone in a space of symmetric matrices.
\newcommand*{\Lnplus}[1][n]{ \mathcal{L}^{{#1}}_{+} }
% The PSD cone in a space of symmetric matrices.
% The PSD cone in a space of Hermitian matrices.
\newcommand*{\Hnplus}[1][n]{ \mathcal{H}^{{#1}}_{+} }
% The PSD cone in a space of Hermitian matrices.
\newcommand*{\Hnplus}[1][n]{ \mathcal{H}^{{#1}}_{+} }