First sample computation
~~~~~~~~~~~~~~~~~~~~~~~~

The computation of the 3D seismograms using the 2D ray-based Born 
approximation in 3 homogenous isotropic models. Each model contains 
two homogenous layers. The models differ only by the shape of the 
interface between the layers. The background is a homogenous isotropic
model without interfaces. The reference seismograms are computed using 
the ray theory.
One computation is prepared in each model. To switch from one
configuration to another change:
m2d-mtt.h ... grid dimensions, model, filenames for CRT
m2d-iwf.h ... grid dimensions
m2d-born.h ... grid dimensions
m2d-ss2.h ... model, data for sp.for
m2d-ss.h ... data for sp.for


History file 'm2d-main.h' is the leading history file. It runs history
files 'm2d-mtt.h', 'm2d-iwf.h', 'm2d-born.h', 'm2d-ss2.h' and 'm2d-ss.h'.

History file 'm2d-mtt.h' computes the perturbations of elastic
parameters, the Green functions from the source and from the receiver,
slowness vectors, travel times and other quantities at the gridpoints.

History file 'm2d-iwf.h' computes the incident wavefield necessary for
the Born approximation using the representation theorem.

History file 'm2d-born.h' computes the 2D Born approximation. The output
file is in the RF format.

History file 'm2d-ss2.h' generates the ray-theory seismogram. 

History file 'm2d-ss.h' generates the Born seismogram from the RF format
file computed by history file 'm2d-born.h' and visualize it together
with the ray-theory seismogram computed by history file 'm2d-ss2.h'.








Second sample computation
~~~~~~~~~~~~~~~~~~~~~~~~~

The computation of the 3D seismograms using the 2D ray-based Born 
approximation in heterogenous model P1-8-10%. The background
model is heterogenous smooth model P1 without interfaces.
The reference seismogram is computed using the ray theory. The observed
differences between the Born and ray-theory seismograms are caused by 
the diffracted waves. Their travel times are marked by 
the green abscissas.

History file 'p1-main.h' is the leading history file. It runs history
files 'p1-grid.h', 'p1-mtt.h', 'p1-iwf.h', 'p1-born.h', 'p1-ss2.h'
and 'p1-ss.h'.

History file 'p1-grid.h' computes the perturbations of the elastic
parameters between the perturbed and background medium. The history file
also generates several pictures.

History file 'p1-mtt.h' computes the Green functions from the source and
from the receiver, slowness vectors, travel times and other quantities
at the gridpoints.

History file 'p1-iwf.h' computes the incident wavefield necessary for
the Born approximation using the representation theorem.

History file 'p1-born.h' computes the 2D Born approximation. The output
file is in the RF format.

History file 'p1-ss2.h' generates the ray-theory seismogram. 

History file 'p1-ss.h' generates the Born seismogram from the RF format
file computed by history file 'p1-born.h' and visualize it together with
the ray-theory seismogram computed by history file 'p1-ss2.h'.
