python setup.py install

  >>> import erfa
  >>> import numpy as np
  >>> pnat = np.array([(-0.76321968546737951,-0.60869453983060384,-0.21676408580639883)])
  >>> v = np.array([(2.1044018893653786e-5,-8.9108923304429319e-5,-3.8633714797716569e-5)])
  >>> s = np.array([0.99980921395708788])
  >>> bm1 = np.array([0.99999999506209258])
  >>> ppr = erfa.ab(pnat, v, s, bm1)
  >>> ppr
  array([[-0.76316311, -0.60875531, -0.21679263]])
  >>> d = np.array([1957.3, 2014.5])
  >>> erfa.besselian_epoch_jd(d)
  (array([ 2400000.5,  2400000.5]), array([ 35948.19151015,  56840.04528042]))