Quasinormal modes from bound states: The numerical approach

It is known that the spectrum of quasinormal modes potential barriers related to bound states corresponding wells. This property has been widely used compute black hole modes, but it limited a few ``approximate'' potentials with certain transformation properties for which must be analytically. In this work we circumvent limitation by proposing an approach allows one make use similar properties, where can also computed numerically. Because numerical calculation usually more stable than direct computation new interesting from technical point view. We apply method different potentials, including P\"oschl-Teller all steps understood analytically, as well are not aware analytic results provide independent comparison. As canonical test, chosen match Regge-Wheeler axial perturbations Schwarzschild hole. find approximate suitable exact quasi-normal potential, particularly first overtone. hope opens perspectives and finds further improvements generalizations in future.