ALGORITHM

The algorithm comprises 5 major routines:

• Logarithmic time interpolation of traces.
• Fourier transformation of interpolated traces.
• DMO step: Convolution in constant frequency plane.
• Inverse Fourier transformation of traces over time axis.
• Inverse logarithmic interpolation of traces.

The outer routines are parallel over time, because Fast Fourier Transformation as well as interpolation require communication between different time samples. The inner routine is identical for each frequency plane. The two-dimensional convolution follows the outline proposed by Biondi 1991. The offset k is laid out serial, because the convolution operator is invariant along the h and $\omega$ axes, but depends on k according to equation (8)

The data organization results in a very efficient code for parallel machines. But, it also requires a transpose step, in which the data layout has to be changed.

On the CM the intrinsic function 'reshape' transposes small data cubes. For data sets, which cannot reside in the CM's distributed memory the transpose could be implemented in the read and write from and to disk.