Separable representations of local potentials

The Ernst-Shakin-Thaler (EST) method which approximates a local potential by one that contains a number of separable terms, by utilizing as basis of expansion a set of states belonging to the discrete and continuous spectrum of the Hamiltonian, is discussed and applied to a simple Yukawa potential and to the Malfliet-Tjon 3S1 potential. A comparison between the off-shell R-matrices and phase-shifts corresponding to the local potentials and those obtained from second and third degree EST approximations was made. A reasonable agreement, particularly with regard to the phase-shifts, was found for energies up to about 150 MeV. The replacement of the state with zero energy by the bound state, in the basis of the EST potential, did not improve the agreement