code: def _taper2coeffs(self, alpha):
          
          taperm = self.orders[alpha]
          coeffs = _np.zeros((2, self.lmax + 1, self.lmax + 1))
          if taperm < 0:
              coeffs[1, :, abs(taperm)] = self.tapers[:, alpha]
          else:
              coeffs[0, :, abs(taperm)] = self.tapers[:, alpha]
  
          return coeffs
docs: Return the spherical harmonic coefficients of the unrotated Slepian
          function i as an array, where i = 0 is the best concentrated function.