An Etymological Dictionary of Astronomy and Astrophysics

A square matrix with a constant value λ (nonzero) along the diagonal, 1’s on the superdiagonal, and all other elements 0.

See also: Named after Marie Ennemond Camille Jordan (1838-1922), French mathematician who pioneered group theory, wrote on the theory of linear differential equations, and on the theory of functions, which he applied to the curve which bears his name. → matrix.