SUBROUTINE INTERS(TDIR,DIRT,WT,WP,ANG)
#
#     COMPUTE INTERSECTION
#
   A1=TDIR/57.29577951
   A2=DIRT/57.29577951
   ANG=ASIN(SIN(A2-A1)*WT/WP)*57.29577951 + TDIR
   RETURN
   END