xsmax

for reflected ray groups specified as L.2 in the array ray, determine the minimum take-off angle using the search mode so that the maximum range for this ray group is xsmax (km) if iturn=0 or the maximum offset of the reflection point is xsmax/2 (km) if iturn=1; for head wave ray groups specified as L.3 in the array ray, the maximum offset of the point of emergence from the head wave boundary is xsmax (km); xsmax=0 will ensure that the take-off angle of the reflected ray which grazes off the bottom of the Lth layer is determined and head waves are traced along the Lth boundary until the edge of the model is reached (default: 0.0)