vec2ang
This IDL facility convert the 3D position vectors of points into their angles
on the sphere.
Location in HEALPix directory tree: src/idl/toolkit/vec2ang.pro
FORMAT
QUALIFIERS

Vector
 input, array,
three dimensional cartesian position vector
(x,y,z) (not necessarily normalised). The north pole is (0,0,1).
The coordinates are ordered as follows

Theta
 output, vector,
vector, colatitude in radians measured southward from north pole in
[0,] (mathematical coordinates).
If ASTRO is set, Theta is the latitude in degrees measured
northward from the equator, in [90, 90] (astronomical coordinates).

Phi
 output, vector,
longitude in radians measured eastward, in [0, ] (mathematical coordinates).
If ASTRO is set, Phi is the longitude in degree measured eastward, in
[0,360] (astronomical coordinates).
KEYWORDS

ASTRO=
 if set Theta and Phi are the latitude and longitude in
degrees (astronomical coordinates) instead of the colatitude and longitude
in radians (mathematical coordinates).
DESCRIPTION
vec2ang performs the geometrical transform from the 3D position vectors
(x,y,z) of
points
into their angles on the sphere:
,
,
RELATED ROUTINES
This section lists the routines related to vec2ang

idl
 version 6.4 or more is necessary to run vec2ang .

pix2xxx, ...
 conversion between vector or angles and pixel index

ang2vec
 conversion from angles to position vectors
EXAMPLE:
Version 3.31, 20170106