Computes all eigenvalues and (optionally) the Schur factorization of a matrix reduced to Hessenberg form.
The routine computes all the eigenvalues, and optionally the Schur factorization, of an upper Hessenberg matrix
Tis an upper triangular (or, for real flavors, quasi-triangular) matrix (the Schur form of
Zis the unitary or orthogonal matrix whose columns are the Schur vectors
You can also use this routine to compute the Schur factorization of a general matrix
Awhich has been reduced to upper Hessenberg form
Qis unitary (orthogonal for real flavors);