chseqr(3) on Linux
The text e9c9c5b09c1c, as Debian 1.3 (Bo) shipped it.
compute the eigenvalues of a complex upper Hessenberg matrix H, and, optionally, the matrices T and Z from the Schur decomposition H = Z T Z**H, where T is an upper triangular matrix (the Schur form), and Z is the unitary matrix of Schur vectors