CSPICE_SURFNM computes the double precision, outward-pointing
normal unit 3-vector at a point defined on the surface of an
For important details concerning this module's function, please refer to
the CSPICE routine surfnm_c.
a, the scalar double precision values of the ellipsoid's
b, triaxial radii ellipsoid, where:
'a' is length in kilometers of the semi-axis of the ellipsoid
parallel to the x-axis of the body-fixed reference frame
'b' is length in kilometers of the semi-axis of the ellipsoid
parallel to the y-axis of the body-fixed reference frame
'c' is length in kilometers of the semi-axis of the ellipsoid
parallel to the z-axis of the body-fixed reference frame
point a double precision 3-vector defining a location on
cspice_surfnm, a, b, c, point, normal
normal a double precision unit 3-vector normal to the
ellipsoid at 'point' in the direction away from the
Any numerical results shown for this example may differ between
platforms as the results depend on the SPICE kernels used as input
and the machine specific arithmetic implementation.
;; Define the radii of an ellipsoid.
a = 1.d
b = 2.d
c = 3.d
;; Select a location.
point = [ 0.d, 0.d, 3.d ]
;; calculate the surface normal to the ellipsoid at 'point'.
cspice_surfnm, a, b, c, point, out_norm
0.0000000 0.0000000 1.0000000
-Icy Version 1.0.0, 16-JUN-2003, EDW (JPL)
surface normal vector on an ellipsoid