Duplicate eigenvectors using SLEPcEigenSolver

Linear Algebra
1

Hi everyone
I am trying to solve a generalized eigenvalue problem using SLEPcEigenSolver. Everything seems to work fine, except that I get duplicate eigenvectors. My code is as follows :

solver = SLEPcEigenSolver(A, B)
solver.parameters["problem_type"] = "pos_gen_non_hermitian"
solver.parameters['spectral_transform'] = 'shift-and-invert'
solver.parameters['spectral_shift'] = 1e-10
solver.solve(50)
k = solver.get_number_converged()
for i in range(k):
    w, _, wx, _ = solver.get_eigenpair(i) 
    # do something with the eigenpair

Is that normal ? Using other solvers such as Matlab or scipy eigs I never get duplicates so that seems weird to me.

Thank you in advance for your help

2

Maybe the duplicates have higher errors than you think? Check by setting:

PETScOptions.set("eps_monitor_all")

and,

set_log_level(LogLevel.TRACE)

.