%
% Standard operations from linear algebra.
%
+\ifx\havemjolinearalgebra\undefined
+\def\havemjolinearalgebra{1}
+
% Needed for \lvert, \rVert, etc. and \operatorname.
\usepackage{amsmath}
% Now declare an orthogonal direct sum in terms of \oplusperp.
\newcommand*{\directsumperp}[2]{ {#1}\oplusperp{#2} }
+
+
+\fi