sfdrays (2.0-git)
2D dynamic ray tracing by a Runge-Kutta integrator.

        sfdrays < vel.rsf > gbeam.rsf shotfile=shots.rsf anglefile=angles.rsf rays=rays.rsf dmat=dmat.rsf proj=proj.rsf mask=mask.rsf vel=y order=4 nt= dt= verb=y shift=0.5 zshot=0. yshot=o[1]+0.5*(n[1]-1)*d[1] nr= a0=0. amax=360.
Angle is 90 deg along y-axis and 180 deg along z-axis, clockwise.

float a0=0.
minimum angle (if no anglefile)
float amax=360.
maximum angle (if no anglefile)
string anglefile=
file with initial angles [nr,nshot] (auxiliary input file name)
string dmat=
auxiliary output file name
float dt=
Sampling in time
string mask=
auxiliary output file name
int nr=
number of angles (if no anglefile)
int nt=
Number of time steps
int order=4
Interpolation order
string proj=
auxiliary output file name
string rays=
auxiliary output file name
float shift=0.5
Complex source shift
string shotfile=
file with shot locations [zshot,yshot,nshot] (auxiliary input file name)
bool vel=y [y/n]
If y, input is velocity; if n, slowness
bool verb=y [y/n]
Verbosity flag
float yshot=o[1]+0.5*(n[1]-1)*d[1]

float zshot=0.