Schur's recursive triangulation procedure
Given a linear endomorphism f on a non-trivial finite-dimensional vector space E over an
algebraically closed field 𝕜, one can always pick an eigenvalue μ of f whose corresponding
eigenspace V is non-trivial. Given that E is also an inner product space, let bV and bW be
othonormal bases for V and Vᗮ respectively. Then, the collection of vectors in bV and bW
forms an othornomal basis bE for E, as the direct sum of V and Vᗮ is an internal
decomposition of E. The matrix representation of f with respect to bE satisfies
$$
\sideset{\mathrm{bE}}{\mathrm{bE}}{[f]} =
\begin{bmatrix}