49 def toUnitXYZ(*, longitude=None, latitude=None, ra=None, dec=None, units):
50 """Compute the unit 3-vectors (as separate arrays) corresponding to
51 arrays of longitude and latitude.
52
53 Parameters
54 ----------
55 longitude : `float` or `numpy.ndarray`
56 Longitude coordinate of input points.
57 latitude : `float` or `numpy.ndarray`
58 Latitude coordinate of input points.
59 ra : `float` or `numpy.ndarray`
60 Synonym for `longitude`.
61 dec : `float` or `numpy.ndarray`
62 Synonym for `latitude`.
63 units : `AngleUnit`
64 Angle unit for inputs.
65
66 Returns
67 -------
68 x : `float` or numpy.ndarray`
69 X coordinates of unit 3-vectors.
70 y : `float` or numpy.ndarray`
71 Y coordinates of unit 3-vectors.
72 z : `float` or numpy.ndarray`
73 Z coordinates of unit 3-vectors.
74
75 Notes
76 -----
77 The returned Cartesian coordinate values are not guaranteed to be
78 normalized according to the conventions of `sphgeom.UnitVector3d`, but
79 are nevertheless compatible with the various vectorized `contains`
80 methods in `sphgeom` because those apply that normalization
81 internally.
82 """
83 factor = (1.0*units).asRadians()
84 lon = factor*_pickExactlyOne(longitude, ra, "Exactly one of ra and longitude must be provided.")
85 lat = factor*_pickExactlyOne(latitude, dec, "Exactly one of dec and latitude must be provided.")
86 return _toUnitX(lon, lat), _toUnitY(lon, lat), _toUnitZ(lon, lat)
