ray_path_point_back_propagation_agenda
======================================

.. currentmodule:: pyarts3.workspace

.. attribute:: Workspace.ray_path_point_back_propagation_agenda
   :type: ~pyarts3.arts.Agenda

   Gets the next past point along a propagation path.

   :attr:`~pyarts3.workspace.Workspace.ray_path` must have a point already.  This point is propagated backwards.

   It is up to internal methods if they respect :attr:`~pyarts3.workspace.Workspace.dispersion_single` or not.

   It is up to internal methods if they respect :attr:`~pyarts3.workspace.Workspace.max_stepsize` or not.

   A special exception may be made for a 1-size :attr:`~pyarts3.workspace.Workspace.ray_path` that is in space or at the surface,
   where the next point may be the same point as the input.

   The end of the path is reached when the last point in :attr:`~pyarts3.workspace.Workspace.ray_path` is
   at :class:`~pyarts3.arts.PathPositionType` ``space`` or ``surface``.

   .. rubric:: Execution and customization

   See :func:`~pyarts3.workspace.Workspace.ray_path_point_back_propagation_agendaSet` for builtin options that selects execution options.

   You can execute :attr:`~pyarts3.workspace.Workspace.ray_path_point_back_propagation_agenda` directly from the workspace by calling :func:`~pyarts3.workspace.Workspace.ray_path_point_back_propagation_agendaExecute`.

   As all agendas in ARTS, it is also customizable via its operator helper class: :class:`~pyarts3.arts.ray_path_point_back_propagation_agendaOperator`.
   See it, :func:`~pyarts3.workspace.Workspace.ray_path_point_back_propagation_agendaSetOperator`, and :func:`~pyarts3.workspace.Workspace.ray_path_point_back_propagation_agendaExecuteOperator` for more details.

   Also see the :class:`~pyarts3.workspace.arts_agenda` property for how to fully define an agenda in python.




   .. rubric:: Agenda output

   .. hlist::
       :columns: 1

       * :attr:`~pyarts3.workspace.Workspace.ray_path_point`

   .. rubric:: Agenda input

   .. hlist::
       :columns: 2

       * :attr:`~pyarts3.workspace.Workspace.ray_path`
       * :attr:`~pyarts3.workspace.Workspace.dispersion_single`
       * :attr:`~pyarts3.workspace.Workspace.propagation_matrix_single`
       * :attr:`~pyarts3.workspace.Workspace.max_stepsize`

   .. rubric:: Default value

   #. Shares the global :attr:`~pyarts3.workspace.Workspace.atmospheric_field`
   #. Shares the global :attr:`~pyarts3.workspace.Workspace.surface_field`
   #. surface_search_accuracy = 0.1
   #. surface_safe_search = 1
   #. :func:`~pyarts3.workspace.Workspace.ray_path_pointPastGeometric`
   #. :func:`~pyarts3.workspace.Workspace.Ignore`, using: input = :attr:`~pyarts3.workspace.Workspace.dispersion_single`
   #. :func:`~pyarts3.workspace.Workspace.Ignore`, using: input = :attr:`~pyarts3.workspace.Workspace.propagation_matrix_single`




   .. rubric:: Input to workspace methods

   .. hlist::
       :columns: 1

       * :func:`~pyarts3.workspace.Workspace.ray_path_point_back_propagation_agendaExecute`
       * :func:`~pyarts3.workspace.Workspace.single_spectral_radianceClearskyEmissionPropagation`
       * :func:`~pyarts3.workspace.Workspace.spectral_radianceClearskyEmissionFrequencyDependentPropagation`


   .. rubric:: Output from workspace methods

   .. hlist::
       :columns: 1

       * :func:`~pyarts3.workspace.Workspace.ray_path_point_back_propagation_agendaSet`
       * :func:`~pyarts3.workspace.Workspace.ray_path_point_back_propagation_agendaSetOperator`


   .. rubric:: Related workspace variables

   .. hlist::
       :columns: 2

       * :attr:`~pyarts3.workspace.Workspace.ray_path`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_absorption_vector_scattering`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_atmospheric_point`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_field`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_frequency_grid`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_frequency_wind_shift_jacobian`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_observer_agenda`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_observers`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_phase_matrix_scattering_spectral`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_point`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_propagation_matrix`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_propagation_matrix_jacobian`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_propagation_matrix_scattering`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_propagation_matrix_source_vector_nonlte`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_propagation_matrix_source_vector_nonlte_jacobian`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_single_frequency`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_single_propagation_matrix`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_single_propagation_matrix_jacobian`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_single_propagation_matrix_nonlte`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_single_propagation_matrix_nonlte_jacobian`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_spectral_radiance_jacobian`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_spectral_radiance_scattering`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_spectral_radiance_source`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_spectral_radiance_source_jacobian`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_suns_path`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_transmission_matrix`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_transmission_matrix_cumulative`
       * :attr:`~pyarts3.workspace.Workspace.ray_path_transmission_matrix_jacobian`

   .. :class:`~pyarts3.arts.Agenda`