Before revision:  Our ZNN based method is coded for sequential and parallel computations and both versions run very accurately and very fast when compared with Johnson's global QR eigenvalue and Bedixon rectangle based method that computes complete eigenanalyses of H\!K {\cal  _A(t_k) for every chosen t_k \in {[} 0,2\pi{]}  .
After revision:  Our ZNN based method is coded for sequential and parallel computations and both versions run very accurately and very fast when compared with Johnson's global QR eigenvalue and Bedixon rectangle based method that computes complete eigenanalyses of {\cal _A(t_k) for every chosen t_k \in {[} 0,2\pi{]} .