calculate_satellite_radial_vector¶

halotools.utils.
calculate_satellite_radial_vector
(sat_hostid, sat_x, sat_y, sat_z, host_halo_id, host_halo_x, host_halo_y, host_halo_z, Lbox)[source] [edit on github]¶ For each satellite, calculate the radial vector pointing from the associated host halo to the satellite, accounting for periodic boundary conditions.
Parameters: sat_hostid : ndarray
Numpy array of integers of shape (num_sats, )
sat_x : ndarray
Numpy array of shape (num_sats, )
sat_y : ndarray
Numpy array of shape (num_sats, )
sat_z : ndarray
Numpy array of shape (num_sats, )
host_halo_id : ndarray
Numpy array of unique integers of shape (num_hosts, )
host_halo_x : ndarray
Numpy array of shape (num_hosts, )
host_halo_y : ndarray
Numpy array of shape (num_hosts, )
host_halo_z : ndarray
Numpy array of shape (num_hosts, )
Lbox : scalar or 3element tuple
periodic boundary conditions
Returns: normalized_radial_vectors : ndarray
Numpy array of shape (num_sats, 3)
Sign convention is such that, for cases where PBCs are not operative, positive values correspond to satellite coordinates being larger than central coordinates, i.e., normalized_radial_vectors[i, 0] = xsat[i]  xcen[i], and so forth.
When PBCs are operative, and the host halo is at the left edge of the box, with the satellite at the right edge, the sign of normalized_radial_vectors will be negative.
radial_distances : ndarray
Numpy array of shape (num_sats, )