code: def solvedbd_sm_c(ah, a, d, axis=4):
      r
  
      return (ah / d) / (inner(ah, (a / d), axis=axis) + 1.0)
docs: r"""
      Compute cached component used by :func:`solvedbd_sm`.
  
      Parameters
      ----------
      ah : array_like
        Linear system component :math:`\mathbf{a}^H`
      a : array_like
        Linear system component :math:`\mathbf{a}`
      d : array_like
        Linear system parameter :math:`\mathbf{d}`
      axis : int, optional (default 4)
        Axis along which to solve the linear system
  
      Returns
      -------
      c : ndarray
        Argument :math:`\mathbf{c}` used by :func:`solvedbd_sm`