The inertia tensor is a real symmetric matrix. A property of real symmetric matrices is that there exists an orientation of the coordinate frame, with its origin at the chosen body-fixed point O , su...The inertia tensor is a real symmetric matrix. A property of real symmetric matrices is that there exists an orientation of the coordinate frame, with its origin at the chosen body-fixed point O , such that the inertia tensor is diagonal. The coordinate system for which the inertia tensor is diagonal is called the Principal axis system which has three perpendicular principal axes.
