Evolution of nonlinear wave groups on water of slowly-varying depth

The aim of this paper is to present quantitative information about the approximate solution of the non-linear Schroedinger equation with varying coefficients and periodic boundary conditions, and comparing it with numerical solutions. A brief review of the method is developed and is based in the evaluation of an "initial disturbance' at every point, and local application of the analytical solution. Quantitative information about the variation of the local "initial disturbance' is provided and we present the comparison of the solution with numerical solutions.