A note on an integrable discretization of the nonlinear Schrodinger equation

In a recent paper (1997 Inverse Problems 13 1121-36); the author suggested a new implementation of an integrable discretization of the nonlinear Schro dinger equation due to Ablowitz and Ladik. The new implementation overcomes the non-locality of the original scheme. In this note it is shown, however , that the proposed scheme suffers from a severe grid-size restriction, whi ch makes it unattractive from a practical viewpoint.