.. _physics-mergerTreeInitializor:

Merger Tree Initializors
========================

Class providing initialization of merger trees---objects that set the initial conditions for the galaxy/halo properties of each node in a newly constructed merger tree before the ODE integration begins. Initialization typically sets the hot gas mass, dark matter halo properties, and other state variables of each node at its formation time, based on the halo mass and the chosen physical model. Multiple initializations can be chained to set up different components independently.

**Default implementation:** ``mergerTreeInitializorStandard``

Methods
-------

``initialize`` → ``void``
   Set the initial conditions for all nodes in the given ``tree``, populating galaxy and halo properties (e.g.\ hot gas mass, dark matter halo state) at each node's formation time before ODE integration proceeds to ``timeEnd``.

   * ``type (mergerTree), intent(inout) :: tree``

   * ``double precision , intent(in ) :: timeEnd``

.. _physics-mergerTreeInitializorStandard:

``mergerTreeInitializorStandard``
---------------------------------

The standard merger tree initializer.

**(Default implementation)**

**Methods**

* ``factors`` — Compute factors needed for tidal tensor calculation.
* ``tidalTensorGet`` — Get the tidal tensor.