Criteria for positive Green's functions

Greens Functions for 3-D Seismic Migration

The space-time Greens functions for 3-D poststack and 3-D prestack migration in a homogeneous medium are derived under the fareld approximation. These Greens functions can be used to practically compute synthetic migrated images. Examples are given for the recording footprint noise associated with a point scatterer and a meandering river channel. The Greens functions also provide fundamental in...

Greens Functions for the Wave Equation

I gather together known results on fundamental solutions to the wave equation in free space, and Greens functions in tori, boxes, and other domains. From this the corresponding fundamental solutions for the Helmholtz equation are derived, and, for the 2D case the semiclassical approximation interpreted back in the time-domain. Utility: scarring via time-dependent propagation in cavities; Math 4...

Report 1 Greens Functions for 3-D Seismic Migration

The space-time Greens functions for 3-D poststack and 3-D prestack migration in a homogeneous medium are derived under the far-field approximation. These Greens functions can be used to practically compute synthetic migrated images. Examples are given for the recording footprint noise associated with a point scatterer and a meandering river channel. The Greens functions also provide fundamental...

Differential Criteria for Positive Definiteness

We show how the Mellin transform can be used to derive differential criteria for integral representations of functions as scale mixtures, and apply this idea to derive differential criteria for positive definiteness of functions in a manner similar to that of Gneiting (1999,2001). We also give a simple derivation of Williamson’s result on multiply monotone functions (Williamson, 1956), with a l...

Genes, greens, and homocysteine.