The weight for the left side of the computational model, , is computed where is extended into the model for a set of grid points. The number of grid points is typically 20, and the values of Table 1 are used for the weight function where .
Table 1: Boundary Weights.
The weights presented by Cerjan  are , where i is the node number for the left side and corresponds to the . The grid index i could be different for the other sides. The weights are applied to all the nodes in the region bounded by to the current time step data, and to the previous time step data after the interior finite differences are computed.