We claim that A and L commute, i.e. LA = AL. It suffices to show that LAx = ALx for all vectors x ∈ ker(A − λj I )αj and all j = 1, . . . , m. Indeed, if x belongs to the generalized eigenspace ker(A − λj I )αj , then Ax lies in the same generalized eigenspace. Therefore, we have Lx = λj x and LAx = λj Ax. Putting these facts together, we obtain LAx = λj Ax = ALx, as claimed. Therefore, we have LA = AL.