Comparison of two schemes

The most computationally intensive part in solving the TTI pure P-wave equation is the FFT calculation, therefore we need to count and compare the total number of FFTs in each scheme. Table 4.2 displays the number of FFTs in modeling one time step using the TTI pure P-wave equation by a standard pseudospectral scheme and the new hybrid scheme. Obviously, the number of FFTs in the hybrid method is reduced by more than half in comparison with that of the pseudospectral method, which indicates that the new hybrid algorithm is computationally efficient compared to the standard pseudospectral scheme. Nevertheless, the disadvantage of the hybrid scheme is that it is not as accurate as the standard pseudospectral scheme.

Table 4.2: Number of FFTs per time step: pseudospectral scheme versus hybrid scheme.

methoddimension	2D	3D
PS	8	14
Hybrid	3	4