Given a real unsymmetric matrix , this routine uses Arnoldi based methods to calculate the eigenvalues , that are of largest absolute value, or are right-most, or are of largest imaginary parts. The right-most eigenvalues are those with the most positive real part. There is an option to compute the associated eigenvectors , , where . The routine may be used to compute the left-most eigenvalues of by using in place of .
The Arnoldi methods oﬀered by EB13 are:
Each method is available in blocked and unblocked form.