code: def _make_complex(self):
          
          rcomplex_coeffs = _shtools.SHrtoc(self.coeffs,
                                            convention=1, switchcs=0)
  
          # These coefficients are using real floats, and need to be
          # converted to complex form.
          complex_coeffs = _np.zeros((2, self.lmax+1, self.lmax+1),
                                     dtype='complex')
          complex_coeffs[0, :, :] = (rcomplex_coeffs[0, :, :] + 1j *
                                     rcomplex_coeffs[1, :, :])
          complex_coeffs[1, :, :] = complex_coeffs[0, :, :].conjugate()
          for m in self.degrees():
              if m % 2 == 1:
                  complex_coeffs[1, :, m] = - complex_coeffs[1, :, m]
  
          # complex_coeffs is initialized in this function and can be
          # passed as reference
          return SHCoeffs.from_array(complex_coeffs,
                                     normalization=self.normalization,
                                     csphase=self.csphase, copy=False)
docs: Convert the real SHCoeffs class to the complex class.