code: def get_polarization_change(self, convert_to_muC_per_cm2=True, all_in_polar=True):
          
          tot = self.get_same_branch_polarization_data(
              convert_to_muC_per_cm2=convert_to_muC_per_cm2, all_in_polar=all_in_polar)
          # reshape to preserve backwards compatibility due to changes
          # when switching from np.matrix to np.array
          return (tot[-1] - tot[0]).reshape((1,  3))
docs: Get difference between nonpolar and polar same branch polarization.