angulardistance
This IDL facility computes the angular distance (in RADIANS) between pairs of vectors.
Location in HEALPix directory tree: src/idl/toolkit/angulardistance.pro
FORMAT
IDL>
distance=angulardistance(V,
W,
[/HELP])
QUALIFIERS

V
 3Dvector (of shape (3) or (1,3)) or list of n 3Dvectors (of shape (n,3))

W
 3Dvector (of shape (3) or (1,3)) or list of n 3Dvectors (of shape
(n,3))
It is not necessary for V and W vectors to be normalised to 1
upon calling the function
If V (and/or W) has the form (n,3,4) (like the pixel corners returned by
pix2vec_*), it should be preprocessed with
V = reform( transpose(V, [0,2,1]), n_elements(V)/3, 3)
before being passed to angulardistance.
KEYWORDS

/HELP
 if set, prints out the help header and exits
DESCRIPTION
After renormalizing the vectors, angulardistance computes the angular distance using
in general, or
when
and
are almost aligned.
If
(resp.
) is a single vector, while
(resp.
) is a list of vectors,
then the result is a list of distances
(resp.
).
If both
and
are lists of vector of the same length,
then the result is a list of distances
.
RELATED ROUTINES
This section lists the routines related to angulardistance

idl
 version 6.4 or more is necessary to run angulardistance.
EXAMPLE:
Version 3.31, 20170106