CSPICE_VSEP returns the separation angle between two 3-vectors.
For important details concerning this module's function, please refer to
the CSPICE routine vsep_c.
v1 is an arbitrary double precision, 3-vector.
v2 is also an arbitrary double precision, 3-vector
'v1' or 'v2' or both may be the zero vector.
An implicit assumption exists that 'v1' and 'v2' lie in the same
reference frame. If this is not the case, the numerical result has
vsep = cspice_vsep( v1, v2 )
vsep the double precision, positive definite, scalar angular separation
between 'v1' and 'v2' expressed in radians. If either 'v1' or 'v2'
is the zero vector, the return value has value zero.
-Icy Version 1.0.4, 03-DEC-2009, EDW (JPL)
Edited header, improved/clarified I/O descriptions.
-Icy Version 1.0.3, 23-SEP-2008, EDW (JPL)
Eliminated grammar error.
-Icy Version 1.0.2, 18-APR-2006, EDW (JPL)
Expanded header comments.
-Icy Version 1.0.1, 09-DEC-2005, EDW (JPL)
Added Examples section.
-Icy Version 1.0.0, 16-JUN-2003, EDW (JPL)
angular separation of 3-dimensional vectors