netsse.model.ship.rollCF
========================

.. py:function:: netsse.model.ship.rollCF(om0, beta_deg, U, L, B0, T, C_B, C_WP, GM_T, kappa, mu, T_N=0)

   Computes the roll transfer function amplitude, using the closed-form
   expressions presented in Jensen et al. (2004).

   :param om0: Vector of absolute wave frequencies [rad/s].
   :type om0: array_like of shape (Nom0,)
   :param beta_deg: Vector of heading angles [deg].
   :type beta_deg: array_like of shape (Nbeta,)
   :param U: Vessel forward speed [m/s].
   :type U: float
   :param L: Length of the ship [m].
   :type L: float
   :param B0: Breadth of the ship [m].
   :type B0: float
   :param T: Draft of the ship [m].
   :type T: float
   :param C_B: Block coefficient of the ship [-].
   :type C_B: float
   :param C_WP: Waterplane area coefficient of the ship [-].
   :type C_WP: float
   :param GM_T: Transverse metacentric height [m].
   :type GM_T: float
   :param kappa: Custom parameter (chosen between 0 and ``C_WP``) representing the ratio
                 between the length of the aft beam and the whole ship length in the
                 simplified ship model for roll.
   :type kappa: float
   :param mu: Ratio between added viscous damping and critical damping.
   :type mu: float, default 0
   :param T_N: Roll natural period [s].

               .. note::
                   If not specified as input, ``T_N`` is calculated using empirical
                   formulas from ADA147598.
   :type T_N: float, optional

   :returns: **roll** -- Coefficients of the roll transfer function amplitude [rad/m].
   :rtype: numpy.ndarray of shape (Nom0,Nbeta)

   .. seealso:: :py:obj:`heaveCF`, :py:obj:`pitchCF`

   .. rubric:: References

   1. Jensen, J. J., Mansour, A. E., & Olsen, A. S. (2004). Estimation of ship
      motions using closed-form expressions. Ocean Engineering, 31(1), 61–85.
      https://doi.org/10.1016/S0029-8018(03)00108-2
   2. ADA147598, 1973. Code of Safety for Fishermen and Fishing Vessels.
      Part B. Safety and Health Requirements for the Construction and Equipment
      of Fishing Vessels. Inter-Governmental Maritime Consultative Organization,
      London, England.

   .. rubric:: Example

   >>> roll = rollCF(om0,beta_deg,U,L,B0,T,C_B,C_WP,GM_T,kappa,mu,T_N=0)