code: def ffPDC(self):
          
          A = self.A()
          return np.abs(A * self.nfft / np.sqrt(np.sum(A.conj() * A, axis=(0, 2),
                                                       keepdims=True)))
docs: Full frequency partial directed coherence.
  
          .. math:: \mathrm{ffPDC}_{ij}(f) =
             \\frac{A_{ij}(f)}{\sqrt{\sum_f A_{:j}'(f) A_{:j}(f)}}