'Return a vector array of the x, y, and z coordinates.
Parameters
xyz_axis : int, optional
The axis in the final array along which the x, y, z components
should be stored (default: 0).
Returns
xyz : `~astropy.units.Quantity`
With dimension 3 along ``xyz_axis``.'

def get_d_xyz(self, xyz_axis=0):

    return _combine_xyz(self._d_x, self._d_y, self._d_z, xyz_axis=xyz_axis)
