CSPICE_VDIST returns the scalar distance between two threedimensional
vectors.
For important details concerning this module's function, please refer to
the CSPICE routine vdist_c.
Given:
vec1,
vec2 two arbitrary double precision 3vectors, the distance between
which is desired.
the call:
dist = cspice_vdistg( vec1, vec2 )
returns:
dist double precision scalar distance between 'vec1' and 'vec2'.
This is defined as
 v1  v2 ,
where  x  indicates the Euclidean norm of the vector x.
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.
v1 = [ 12.3d , 4.32d , 76.d ]
v2 = [ 23.0423d, 11.99d, 0.10d ]
print, cspice_vdist( v1, v2)
IDL outputs:
77.236234
Native IDL code to calculate the same scalar result:
norm( v1  v2 )
The IDL function accepts an arbitrary size Nvectors.
The Euclidean norm of a threedimensional vector (x, y, z) is
defined as
1/2
2 2 2
( x + y + z ).
This number is the distance of the point (x, y, z) from the
origin. If A and B are two vectors whose components are
( a[0], a[1], a[2] ) and ( b[0], b[1], b[2] ),
then the distance between A and B is the norm of the difference
A  B, which has components
( a[0]  b[0], a[1]  b[1], a[2]  b[2] ).
A related routine is cspice_vdistg, which computes the distance between
two vectors of general dimension.
ICY.REQ
Icy Version 1.0.2, 13JUN2011, EDW (JPL)
Edits to comply with NAIF standard for Icy headers.
Corrected version ID for 18APR2006 entry "1.0.1"
rather than "1.0.2."
Icy Version 1.0.1, 18APR2006, EDW (JPL)
Expanded header comments.
Icy Version 1.0.0, 16JUN2003, EDW (JPL)
distance between 3dimensional vectors
