surfnm_c |

Table of contents## Proceduresurfnm_c ( Surface normal vector on an ellipsoid ) void surfnm_c ( SpiceDouble a, SpiceDouble b, SpiceDouble c, ConstSpiceDouble point[3], SpiceDouble normal[3] ) ## AbstractCompute the outward-pointing, unit normal vector at a point on the surface of an ellipsoid. ## Required_ReadingNone. ## KeywordsELLIPSOID GEOMETRY ## Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- a I Length of the ellipsoid semi-axis along the X-axis. b I Length of the ellipsoid semi-axis along the Y-axis. c I Length of the ellipsoid semi-axis along the Z-axis. point I Body-fixed coordinates of a point on the ellipsoid. normal O Outward pointing unit normal to ellipsoid at `point'. ## Detailed_Inputa is the length of the semi-axis of the ellipsoid that is parallel to the X-axis of the body-fixed reference frame. b is the length of the semi-axis of the ellipsoid that is parallel to the Y-axis of the body-fixed reference frame. c is the length of the semi-axis of the ellipsoid that is parallel to the Z-axis of the body-fixed reference frame. point is a 3-vector giving the bodyfixed coordinates of a point on the ellipsoid. In bodyfixed coordinates, the semi-axes of the ellipsoid are aligned with the X, Y, and Z-axes of the reference frame. ## Detailed_Outputnormal is the unit vector pointing away from the ellipsoid and normal to the ellipsoid at `point'. ## ParametersNone. ## Exceptions1) If any of the axes are non-positive, the error SPICE(BADAXISLENGTH) is signaled by a routine in the call tree of this routine. ## FilesNone. ## ParticularsThis routine computes the outward pointing unit normal vector to the ellipsoid having semi-axes of length `a', `b', and `c' from the point `point'. ## ExamplesA typical use of ## Restrictions1) It is assumed that the input point is indeed on the ellipsoid. No checking for this is done. ## Literature_ReferencesNone. ## Author_and_InstitutionN.J. Bachman (JPL) J. Diaz del Rio (ODC Space) B.V. Semenov (JPL) ## Version-CSPICE Version 1.3.2, 01-NOV-2021 (JDR) Edited the header to comply with NAIF standard. Updated the documentation to refer to "reference frame" instead of "coordinate system" as per NAIF conventions. -CSPICE Version 1.3.1, 31-JAN-2008 (BVS) Removed '-Revisions' from the header. -CSPICE Version 1.3.0, 22-OCT-1998 (NJB) Made input vector const. -CSPICE Version 1.2.0, 08-FEB-1998 (NJB) Removed local variables used for temporary capture of outputs. -CSPICE Version 1.0.0, 25-OCT-1997 (NJB) Based on SPICELIB Version 1.2.0, 07-AUG-1996 (WLT) ## Index_Entriessurface normal vector on an ellipsoid |

Fri Dec 31 18:41:13 2021