'Angular diameter distance in Mpc at a given redshift.
This gives the proper (sometimes called \'physical\') transverse
distance corresponding to an angle of 1 radian for an object
at redshift ``z``.
Weinberg, 1972, pp 421-424; Weedman, 1986, pp 65-67; Peebles,
1993, pp 325-327.
Parameters
z : array-like
Input redshifts.  Must be 1D or scalar.
Returns
d : `~astropy.units.Quantity`
Angular diameter distance in Mpc at each input redshift.'

def angular_diameter_distance(self, z):

    if isiterable(z):
        z = np.asarray(z)
    return (self.comoving_transverse_distance(z) / (1.0 + z))
