.. index:: pair: struct; rgpot::nlist::CellGrid
.. _doxid-structrgpot_1_1nlist_1_1_cell_grid:

struct rgpot::nlist::CellGrid
=============================

.. toctree::
	:hidden:

Overview
~~~~~~~~

Cell decomposition of one configuration: atoms sorted by cell (CSR). :ref:`More...<details-structrgpot_1_1nlist_1_1_cell_grid>`


.. ref-code-block:: cpp
	:class: doxyrest-overview-code-block

	#include <cell_visit.hpp>
	
	struct CellGrid {
		// fields
	
		std::array<int, 3> :target:`nc<doxid-structrgpot_1_1nlist_1_1_cell_grid_1ac97e27795326e60243def639fd8e055e>` {{1, 1, 1}};
		std::array<bool, 3> :target:`wrap<doxid-structrgpot_1_1nlist_1_1_cell_grid_1a181aa3a6ac2c4da69148465c634b56bc>` {{false, false, false}};
		std::vector<int32_t> :ref:`start<doxid-structrgpot_1_1nlist_1_1_cell_grid_1a616d9b2141605534a91cf1be712b58eb>`;
		std::vector<int32_t> :ref:`atoms<doxid-structrgpot_1_1nlist_1_1_cell_grid_1a006789da87e1569d7de2744ea62f855e>`;

		// methods
	
		long :ref:`neighbour<doxid-structrgpot_1_1nlist_1_1_cell_grid_1abba1e64fa51fe4e82110c395a7f366d7>`(int cx, int cy, int cz, const int o[3]) const;
		bool :ref:`build<doxid-structrgpot_1_1nlist_1_1_cell_grid_1a8325e8f4b5bd62f82b8922074de0cca8>`(const double* points, std::size_t n, const double w[3], const double inv[3], double rl);
	};
.. _details-structrgpot_1_1nlist_1_1_cell_grid:

Detailed Documentation
~~~~~~~~~~~~~~~~~~~~~~

Cell decomposition of one configuration: atoms sorted by cell (CSR).

Fields
------

.. index:: pair: variable; start
.. _doxid-structrgpot_1_1nlist_1_1_cell_grid_1a616d9b2141605534a91cf1be712b58eb:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	std::vector<int32_t> start

ncells + 1 row starts into ``atoms``.

.. index:: pair: variable; atoms
.. _doxid-structrgpot_1_1nlist_1_1_cell_grid_1a006789da87e1569d7de2744ea62f855e:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	std::vector<int32_t> atoms

Atom indices grouped by cell.

Methods
-------

.. index:: pair: function; neighbour
.. _doxid-structrgpot_1_1nlist_1_1_cell_grid_1abba1e64fa51fe4e82110c395a7f366d7:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	long neighbour(int cx, int cy, int cz, const int o[3]) const

Linear index of cell (cx, cy, cz) shifted by stencil offset ``o``, or -1 when the shift leaves a free axis.

.. index:: pair: function; build
.. _doxid-structrgpot_1_1nlist_1_1_cell_grid_1a8325e8f4b5bd62f82b8922074de0cca8:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	bool build(const double* points, std::size_t n, const double w[3], const double inv[3], double rl)

Bin ``points`` into cells no narrower than ``rl``. ``w[k]`` is the periodic width and ``inv[k]`` its inverse, zero for a free axis. Returns false when a grid cannot serve (fewer than three cells along a periodic axis, or fewer than kMinCellsForGrid cells in all) or would not pay (the cell scan's pair tests for this occupancy, plus the stencil walk, above half the brute-force scan's n (n - 1) / 2: a cluster in a mostly empty box crowds a few cells), in which case the caller uses the brute-force scan.