gistfile1.py

...

from slepc4py import SLEPc

A = assemble(a).M.handle

eps = SLEPc.EPS().create()

# eps.setDimensions(nev=10, ncv=100)

# eps.setWhichEigenpairs(eps.Which.SMALLEST_MAGNITUDE)
eps.setOperators(A)

eps.setFromOptions()
eps.solve()

n = eps.getConverged()

for i in range(n):
    val = eps.getEigenvalue(i)
    print val