mirror_latlon Subroutine

 subroutine mirror_latlon(lon1, lat1, lon2, lat2, lon0, lat0, lon3, lat3)
!
! Given the "mirror" as defined by (lon1, lat1), (lon2, lat2), and center 
! of the sphere, compute the mirror image of (lon0, lat0) as  (lon3, lat3)

 real(ESMF_KIND_R8), intent(in):: lon1, lat1, lon2, lat2, lon0, lat0
 real(ESMF_KIND_R8), intent(out):: lon3, lat3
!
 real(ESMF_KIND_R8) p0(3), p1(3), p2(3), nb(3), pp(3), sp(2)
 real(ESMF_KIND_R8) pdot
 integer k

 call latlon2xyz2(lon0, lat0, p0)
 call latlon2xyz2(lon1, lat1, p1)
 call latlon2xyz2(lon2, lat2, p2)
 call vect_cross(nb, p1, p2)

 pdot = sqrt(nb(1)**2+nb(2)**2+nb(3)**2)
 do k=1,3
    nb(k) = nb(k) / pdot
 enddo

 pdot = p0(1)*nb(1) + p0(2)*nb(2) + p0(3)*nb(3)
 do k=1,3
    pp(k) = p0(k) - 2.*pdot*nb(k)
 enddo

 call cart_to_latlon(1, pp, sp(1), sp(2))
 lon3 = sp(1)
 lat3 = sp(2)

 end subroutine  mirror_latlon