Program sfirays | Fast marching for image rays 
[SYNOPSIS]
sfirays < in.rsf > out.rsf t0=ot0.rsf x0=ox0.rsf f0=of0.rsf velocity=y order=1 thres=10.
[PARAMETERS]
string  | f0 | = |   | 	auxiliary output file name
int     | order | =1 |   | 	fastmarching accuracy order 
string  | t0 | = |   | 	auxiliary output file name
float   | thres | =10. |   | 	thresholding for caustics 
bool    | velocity | =y |  [y/n] | 	y, inputs are velocity / n, slowness-squared 
string  | x0 | = |   | 	output upwind neighbor (auxiliary output file name)
[DIRECTORY]
user/llisiw
