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/**
* @file tree.h
* @brief Tree header file. All the tree implementations needed by other routines.
* @author Shangfei Liu <liushangfei@pku.edu.cn>, Hanno Rein <hanno@hanno-rein.de>
*
* @section LICENSE
* Copyright (c) 2011 Hanno Rein, Shangfei Liu
*
* This file is part of rebound.
*
* rebound is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* rebound is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with rebound. If not, see <http://www.gnu.org/licenses/>.
*
*/
#ifndef _TREE_H
#define _TREE_H
struct reb_treecell;
/**
* @brief The data structure of one node of a tree
*/
struct reb_treecell {
double x; /**< The x position of the center of a cell */
double y; /**< The y position of the center of a cell */
double z; /**< The z position of the center of a cell */
double w; /**< The width of a cell */
double m; /**< The total mass of a cell */
double mx; /**< The x position of the center of mass of a cell */
double my; /**< The y position of the center of mass of a cell */
double mz; /**< The z position of the center of mass of a cell */
#ifdef QUADRUPOLE
double mxx; /**< The xx component of the quadrupole tensor of mass of a cell */
double mxy; /**< The xy component of the quadrupole tensor of mass of a cell */
double mxz; /**< The xz component of the quadrupole tensor of mass of a cell */
double myy; /**< The yy component of the quadrupole tensor of mass of a cell */
double myz; /**< The yz component of the quadrupole tensor of mass of a cell */
double mzz; /**< The zz component of the quadrupole tensor of mass of a cell */
#endif // QUADRUPOLE
struct reb_treecell *oct[8]; /**< The pointer array to the octants of a cell */
int pt; /**< It has double usages: in a leaf node, it stores the index
* of a particle; in a non-leaf node, it equals to (-1)*Total
* Number of particles within that cell. */
int remote; /**< 0 by default. Set to 1 if this cell is part of an essential tree (MPI).*/
};
/**
* @brief This function updates the tree.
* @details The tree needs to be updated when particles move, this function does that.
* @param r Rebound simulation to operate on
*/
void reb_simulation_update_tree(struct reb_simulation* const r);
/**
* @brief The wrap function calls reb_simulation_update_tree_gravity_data_in_cell() for each tree.
* @param r Rebound simulation to operate on
*/
void reb_simulation_update_tree_gravity_data(struct reb_simulation* const r);
/**
* @brief The wrap function calls reb_tree_add_particle_to_cell() to add the particle into one of the trees. If the tree_root doesn't exist, then it initializes the tree.
* @param r Rebound simulation to operate on
* @param pt Index of a particle.
*/
void reb_tree_add_particle_to_tree(struct reb_simulation* const r, int pt);
/**
* @brief Free up all space occupied by the tree structure.
* This will not modify particles.
* @param r Rebound simulation to operate on
*/
void reb_tree_delete(struct reb_simulation* const r);
#ifdef MPI
/**
* @brief MPI related function used to calculate gravity from nearby nodes
* @param node is a pointer to a node cell.
*/
void reb_tree_add_essential_node(struct reb_simulation* const r, struct reb_treecell* node);
/**
* @brief MPI related function used to calculate gravity from nearby nodes
*/
void reb_tree_prepare_essential_tree_for_gravity(struct reb_simulation* const r);
/**
* @brief MPI related function used to calculate gravity from nearby nodes
*/
void reb_tree_prepare_essential_tree_for_collisions(struct reb_simulation* const r);
#endif // MPI
#endif // _TREE_H