ray

an array containing the ray groups to be traced; the following code is used:
(1) L.1 - rays which refract (turn) in the Lth layer
(2) L.2 - rays which reflect off the bottom of the Lth layer
(3) L.3 - rays which travel as head waves along the bottom of the Lth layer
(4) L.0 - ray take-off angles supplied by the user in the arrays amin and amax