docs: def ckm_wolfenstein(laC, A, rhobar, etabar):
      r"""CKM matrix in the Wolfenstein parametrization and standard phase
      convention.
  
      This function does not rely on an expansion in the Cabibbo angle but
      defines, to all orders in $\lambda$,
  
      - $\lambda = \sin\theta_{12}$
      - $A\lambda^2 = \sin\theta_{23}$
      - $A\lambda^3(\rho-i \eta) = \sin\theta_{13}e^{-i\delta}$
  
      where $\rho = \bar\rho/(1-\lambda^2/2)$ and
      $\eta = \bar\eta/(1-\lambda^2/2)$.
  
      Parameters
      ----------
  
      - `laC`: Wolfenstein parameter $\lambda$ (sine of Cabibbo angle)
      - `A`: Wolfenstein parameter $A$
      - `rhobar`: Wolfenstein parameter $\bar\rho = \rho(1-\lambda^2/2)$
      - `etabar`: Wolfenstein parameter $\bar\eta = \eta(1-\lambda^2/2)$
      """
      rho = rhobar/(1 - laC**2/2.)
      eta = etabar/(1 - laC**2/2.)
      return np.array([[sqrt(1 - laC**2)*sqrt(1 - A**2*laC**6*((-1j)*eta + rho)*((1j)*eta + rho)),
          laC*sqrt(1 - A**2*laC**6*((-1j)*eta + rho)*((1j)*eta + rho)),
          A*laC**3*((-1j)*eta + rho)],
          [-(laC*sqrt(1 - A**2*laC**4)) - A**2*laC**5*sqrt(1 - laC**2)*((1j)*eta + rho),
          sqrt(1 - laC**2)*sqrt(1 -  A**2*laC**4) - A**2*laC**6*((1j)*eta + rho),
          A*laC**2*sqrt(1 - A**2*laC**6*((-1j)*eta + rho)*((1j)*eta + rho))],
          [A*laC**3 - A*laC**3*sqrt(1 - laC**2)*sqrt(1 - A**2*laC**4)*((1j)*eta + rho),
          -(A*laC**2*sqrt(1 - laC**2)) - A*laC**4*sqrt(1 - A**2*laC**4)*((1j)*eta + rho),
          sqrt(1 - A**2*laC**4)*sqrt(1 - A**2*laC**6*((-1j)*eta + rho)*((1j)*eta + rho))]])