swiift.api.spectra
==================

.. py:module:: swiift.api.spectra

.. autoapi-nested-parse::

   Consistant implementations of usual spectral formulations.

   Spectra are defined as function of the frequency. Definitions are taken
   from [1]_.

   .. rubric:: References

   .. [1] Stansberg, Carl Trygve & Contento, G. & Hong, S.W. & Irani, M. &
      Ishida, S. & Mercier, R.. (2002). The specialist committee on waves
      final report and recommendations to the 23rd ITTC. Proceedings of the
      23rd ITTC. 505-736.



Classes
-------

.. autoapisummary::

   swiift.api.spectra.PiersonMoskowitz
   swiift.api.spectra.Bretschneider
   swiift.api.spectra.JONSWAP


Module Contents
---------------

.. py:class:: PiersonMoskowitz

   Bases: :py:obj:`_PMFamily`


   Class encapsulating the Pierson--Moskowitz spectrum.


   .. py:method:: from_swh(swh, gravity)
      :classmethod:


      Build a spectrum parameterised by the SWH.

      :param swh: Significant wave height, in m.
      :type swh: float
      :param gravity: Acceleration of gravity, in m s**-2.
      :type gravity: float

      :returns: Initialised spectrum object.
      :rtype: PiersonMoskowitz



   .. py:method:: from_peak_frequency(peak_frequency, gravity)
      :classmethod:


      Build a spectrum parameterised by the peak frequency.

      :param peak_frequency: Peak frequency, in Hz.
      :type peak_frequency: float
      :param gravity: Acceleration of gravity, in m s^-2.
      :type gravity: float

      :returns: Initialised spectrum object.
      :rtype: PiersonMoskowitz



.. py:class:: Bretschneider

   Bases: :py:obj:`_PMFamily`


   Class encapsulating the Bretschneider spectrum.


   .. py:method:: from_peak_frequency_swh(peak_frequency, swh)
      :classmethod:


      Build a spectrum parameterised by peak frequency and SWH.

      :param peak_frequency: Peak frequency, in Hz.
      :type peak_frequency: float
      :param swh: Significant wave height, in m.
      :type swh: float

      :returns: Initialised spectrum.
      :rtype: Bretschneider



.. py:class:: JONSWAP

   Bases: :py:obj:`_UnimodalSpectrum`


   Class encapsulating the JONSWAP spectrum.

   The JONSWAP spectrum modifies the PM spectrum by introducing a peak
   enhancement factor.

   .. attribute:: peakedness

      

      :type: float

   .. attribute:: _base_spectrum

      

      :type: PiersonMoskowitz


   .. py:property:: peak_frequency
      :type: float


      Peak frequency.

      :returns: Peak frequency, in Hz.
      :rtype: float


   .. py:method:: swh()

      Significant wave height.

      The SWH is computed with a cubic approximation.

      :returns: Significant wave height, in m.
      :rtype: float



   .. py:method:: from_parameters(peak_frequency, peakedness, gravity)
      :classmethod:


      Build a spectrum.

      Peak frequency and gravity are used to instantiate the
      underlying Pierson--Moskowitz spectrum, while peakedness is
      specific to the JONSWAP formulation.

      :param peak_frequency: Peak frequency, in Hz.
      :type peak_frequency: float
      :param peakedness: Peakedness (base of the peak enhancement factor).
      :type peakedness: float
      :param gravity: Acceleration of gravity, in m s^-2.
      :type gravity: float

      :returns: Initialised spectrum.
      :rtype: JONSWAP



   .. py:method:: density(frequency)

      Spectral density as a function of frequency.

      :param frequency: Frequency at which to evaluate the density.
      :type frequency: array_like

      :returns: **density** -- The density in m^2 s.
      :rtype: float or np.ndarray