2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/138096A strengthened form of Schur's triangularization theorem is given for quaternion matrices with real spectrum (for complex matrices it was given by Littlewood). Littlewood's algorithm for reducing a complex matrix to a canonical form under unitary similarity is extended to quaternion matrices whose eigenvalues have geometric multiplicity 1.20 pagesRepresentation Theory15A21text