sfrays2a (3.0)
Ray tracing in VTI media by a Runge-Kutta integrator.

        sfrays2a < vz.rsf > rays.rsf shotfile=shots.rsf anglefile=angles.rsf vel=y order=4 nt= dt= verb=y escvar=n zshot=0. yshot=o[1] + 0.5*(n[1]-1)*d[1] nr= a0=0. amax=360. vx= eta= > rays.rsf
Rays can be plotted with sfplotrays.

float a0=0.
minimum angle (if no anglefile)
float amax=360.
maximum angle (if no anglefile)
string anglefile=
file with initial angles (auxiliary input file name)
float dt=
Sampling in time
bool escvar=n [y/n]
If y - output escape values, n - trajectories
string eta=
eta parameter
int nr=
number of angles (if no anglefile)
int nt=
Number of time steps
int order=4
Interpolation order
string shotfile=
file with shot locations (auxiliary input file name)
bool vel=y [y/n]
If y, input is velocity; if n, slowness
bool verb=y [y/n]
Verbosity flag
string vx=
horizontal velocity or slowness
float yshot=o[1] + 0.5*(n[1]-1)*d[1]

float zshot=0.
shot coordinates (if no shotfile)