Computes for an N-by-N nonsymmetric matrix A, the eigenvalues, the Schur form T, and, optionally, the matrix of Schur vectors VS. This gives the Schur factorization A = VS*T*(VS**H). 

Optionally the routine also orders the eigenvalues on the diagonal of the Schur form so that selected eigenvalues are at the top left. The Select function parameters accepts a function with two parameters. First is the real and the second is the imaginary part of the eigenvalue. The function is to return true, if the specified eigenvalue is to be included in to sorting at the top left of the Schur form. If sorting is not required pass nil (NULL) for this parameter.

EigSchure Method