code: def iau2000a(jd_tt):
      
      # Interval between fundamental epoch J2000.0 and given date.
  
      t = (jd_tt - T0) / 36525.0
  
      # Compute fundamental arguments from Simon et al. (1994), in radians.
  
      a = fundamental_arguments(t)
  
      # ** Luni-solar nutation **
      # Summation of luni-solar nutation series (in reverse order).
  
      arg = nals_t.dot(a)
      fmod(arg, tau, out=arg)
  
      sarg = sin(arg)
      carg = cos(arg)
  
      stsc = array((sarg, t * sarg, carg)).T
      ctcs = array((carg, t * carg, sarg)).T
  
      dpsi = tensordot(stsc, lunisolar_longitude_coefficients)
      deps = tensordot(ctcs, lunisolar_obliquity_coefficients)
  
      # Compute and add in planetary components.
  
      if getattr(t, 'shape', ()) == ():
          a = t * anomaly_coefficient + anomaly_constant
      else:
          a = (outer(anomaly_coefficient, t).T + anomaly_constant).T
      a[-1] *= t
  
      fmod(a, tau, out=a)
      arg = napl_t.dot(a)
      fmod(arg, tau, out=arg)
      sc = array((sin(arg), cos(arg))).T
  
      dpsi += tensordot(sc, nutation_coefficients_longitude)
      deps += tensordot(sc, nutation_coefficients_obliquity)
  
      return dpsi, deps
docs: Compute Earth nutation based on the IAU 2000A nutation model.
  
      `jd_tt` - Terrestrial Time: Julian date float, or NumPy array of floats
  
      Returns a tuple ``(delta_psi, delta_epsilon)`` measured in tenths of
      a micro-arcsecond.  Each value is either a float, or a NumPy array
      with the same dimensions as the input argument.