Eigensolver default solver

Hi,

as google searches lead mostly to deleted pages of the old documentation and don’t answer my question, i would like to know what the deafult solving algorithm for calculating eigenvalues is.
In my code i don’t furhter specify a solver e.g.:

 a = dot(grad(u), grad(v))*dx 
 L_dummy = Constant(0)*v*dx
 m = u*v*dx

 A, _ = assemble_system(a,L_dummy,bc)
 B = assemble(m)
 eigensolver = SLEPcEigenSolver(as_backend_type(A), as_backend_type(B))
 eigensolver.parameters['spectrum'] = 'target real'
 eigensolver.parameters['tolerance'] = 1e-6
 eigensolver.solve()
 r, c, rx, cx = eigensolver.get_eigenpair(0)
 print("Eigenvalue: ", r, " + ",c,"i")

As slepc is the backend, it uses the default solver from SLEPc, see section 2.4 of: https://slepc.upv.es/documentation/slepc.pdf
The options are also listed in: https://bitbucket.org/fenics-project/dolfin/src/b495043d6b3914383eb939ea6c6794442080a3a5/dolfin/la/SLEPcEigenSolver.cpp?at=master#lines-492:523