HOW ARE WE GOING TO GET THE PEF?

How are we going to get the PEF? I propose we invoke stationarity and scale invariance. Notice that we have an interesting kind of scale invariance here. We can expand the correct PEF and it is still a correct PEF. (It is interesting to notice that an apparent scale or resonant spectrum visible along the observation track does not prevent the 2-D function from being scale invariant).

We have a non-linear optimization problem to solve. You know it, $0\approx A(Z)P(Z)$ where a₀=1 and some of the p_i are known. It is non-linear. This problem is linearized in Claerbout (1992) and Claerbout (2000) but I don't trust an ignorant descent. I've had some disappointments doing that (but that was before I learned about scale invariance). How would you try?