I am trying to find the eigenvalues and -vectors of a large-ish (4400x4400 elements) sparse matrix using eigs().
When I define a small subset of eigenvalues to be found, e.g. 20 values with the largest imaginary part (option 'li'), the algorithm takes too long to converge. If I request almost all eigenvalues to be found, I manage to get a correct answer. At least, sometimes.
More often than not I get back the error below. This seems to be dependent on the number of eigenvalues I request. It works for k=3000 but not for k=4000 or k=2500.
Error using eigs (line ###)
Error with ARPACK routine znaupd: info = -8
Error return from LAPACK eigenvalue calculation;
This description doesn't help me at all to pin point what goes wrong and what I can change to avoid getting these errors.
Can anyone tell me what exactly triggers this error, and how I fix my matrices/problem to avoid it?