Program sftimecont | Forward or reverse time continuation using fast marching. 
[SYNOPSIS]
sftimecont < vel.rsf > time.rsf surf=time0.rsf forwd=n vel=y order=2
[PARAMETERS]
bool    | forwd | =n |  [y/n] | 	continue forward or backward 
int     | order | =2 |  [1,2] | 	Accuracy order 
file    | surf | = |   | 	auxiliary input file name
bool    | vel | =y |  [y/n] | 	if y, the input is velocity; n, slowness squared 
[DIRECTORY]
user/fomels
