netsse.analys.buoy.spread_dist_params2Fourier
=============================================

.. py:function:: netsse.analys.buoy.spread_dist_params2Fourier(alpha, sigma, gamma, delta, unit='rad')

   Infers the Fourier coefficients from the parameters of the directional
   spreading distribution function, as per Kuik et al. (1988).

   :param alpha: Wave direction [rad, or deg].
   :type alpha: array_like of shape (Nf,)
   :param sigma: Directional spread [rad, or deg].
   :type sigma: array_like of shape (Nf,)
   :param gamma: Skewness of the directional distribution [-].
   :type gamma: array_like of shape (Nf,)
   :param delta: Kurtosis of the directional distribution [-].
   :type delta: array_like of shape (Nf,)
   :param unit: Unit of the wave direction and directional spread: ``'deg'`` or ``'rad'``
                (default).
   :type unit: {'rad','deg'}, optional

   :returns: **a1, b1, a2, b2** -- First four Fourier coefficients of the directional wave spectrum.
   :rtype: array_like of shape (Nf,)

   .. seealso::

      :py:obj:`Fourier2spread_dist_params`
          Infers the parameters of the directional spreading distribution function from the Fourier coefficients.

      :py:obj:`Shannon_MEMII_Newton`
          Reconstructs the directional spreading function based on the first four Fourier coefficients of a directional wave spectrum.

   .. rubric:: References

   Kuik, A. J., van Vledder, G. P., & Holthuijsen, L. H. (1988). *A Method for
   the Routine Analysis of Pitch-and-Roll Buoy Wave Data*. Journal of Physical
   Oceanography, 18(7), 1020–1034.

   .. rubric:: Example

   >>> [a1,b1,a2,b2] = spread_dist_params2Fourier(alpha,sigma,gamma,delta,unit)