Program sfdrays | 2D dynamic ray tracing by a Runge-Kutta integrator. 
[SYNOPSIS]
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.
[COMMENTS]
Angle is 90 deg along y-axis and 180 deg along z-axis, clockwise.

[PARAMETERS]
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. |   | 	
[DIRECTORY]
user/llisiw
