Implicit finite-difference migration

The third and final test benchmarking test was the migration of 2-D prestack and 3-D poststack datasets with implicit finite-differences. The code used for these tests was developed to implement a range of wavefield extrapolation operators, including implicit finite-difference migration in the helical coordinate system Rickett et al. (1998).

For these benchmarking test cases, we used the 65 operator described by Lee and Suh (1985), and for the 3-D test, rather than inverting the full extrapolation matrix, we made the splitting approximation. We used the LAPACK Anderson et al. (1995) subroutine cgtsv to solve the resulting tridiagonal systems.