One-pass PSPI

By using the PSPI algorithmGazdag and Sguazzero (1984), the wave extrapolation with lateral velocity variations can be implemented. I first use v₁ and v₂ to do the wave extrapolation separately, then inverse Fourier transform the wave field to the space domain. Then I interpolate the wavefield between $U_{1}(\omega,z+\Delta z,y)$ and $U_{2}(\omega,z+\Delta z,y)$. Finally, I do the Fourier transform again to complete the next $\Delta z$ wavefield extrapolation in the same way. Figure 1 is a computational flow chart of this process.