Comment on: "On the characteristic polynomial of an effective Hamiltonian"
arXiv:2209.10112 · doi:10.1016/j.physleta.2022.128456
Abstract
We show that a method proposed recently, based on the characteristic polynomial of an effective Hamiltonian, had been developed several years earlier by other authors in a clearer and more general way. We outline both implementations of the approach and compare them by means of the calculation of the exceptional point closest to origin for a toy model.