A matrix, also called a canonical box matrix, having zeros everywhere except along the diagonal and superdiagonal,
with each element of the diagonal consisting of a single
number ,
and each element of the superdiagonal consisting
of a 1. For example,
(Ayres 1962, p. 206).
Note that the degenerate case of a matrix is considered a Jordan block even though it
lacks a superdiagonal to be filled with 1s (Strang
1988, p. 454).