GBBEAM - Gaussian beam synthetic seismograms for a sloth model

gbbeam <rayends >syntraces xg= zg= [optional parameters]

Required Parameters:
xg= x coordinates of receiver surface
zg= z coordinates of receiver surface

Optional Parameters:
ng=101 number of receivers (uniform distributed along surface)
krecord=1 integer index of receiver surface (see notes below)
ang=0.0 array of angles corresponding to amplitudes in amp
amp=1.0 array of amplitudes corresponding to angles in ang
bw=0 beamwidth at peak frequency
nt=251 number of time samples
dt=0.004 time sampling interval
ft=0.0 first time sample
reftrans=0 =1 complex refl/transm. coefficients considered
prim =1, only single-reflected rays are considered ",
=0, only direct hits are considered
atten=0 =1 add noncausal attenuation
=2 add causal attenuation
lscale= if defined restricts range of extrapolation
aperture= maximum angle of receiver aperture
fpeak=0.1/dt peak frequency of ricker wavelet
infofile ASCII-file to store useful information
NOTES:
Only rays that terminate with index krecord will contribute to the
synthetic seismograms at the receiver (xg,zg) locations. The
receiver locations are determined by cubic spline interpolation
of the specified (xg,zg) coordinates.



AUTHOR: Dave Hale, Colorado School of Mines, 02/09/91
MODIFIED: Andreas Rueger, Colorado School of Mines, 08/18/93
Modifications include: 2.5-D amplitudes, computation of reflection/
transmission losses, attenuation,
timewindow, lscale, aperture, beam width, etc.