Cell¶

class dolfin.cpp.mesh.Cell(*args)¶

Bases: dolfin.cpp.mesh.MeshEntity

A Cell is a MeshEntity of topological codimension 0.

Create cell on given mesh with given index

Parameters:	Mesh & mesh (const) – The mesh. index (std::size_t) – The index.

cell_normal()¶

Compute normal to cell itself (viewed as embedded in 3D)

Return type:	Point
Returns:	`Point` Normal of the cell

circumradius()¶

Compute circumradius of cell

UnitSquareMesh mesh(1, 1);
Cell cell(mesh, 0);
info("%g", cell.circumradius());

Return type:	double
Returns:	double The circumradius of the cell.

collides()¶

Check whether given point collides with cell

Parameters:	Point & point (const) – The point to be checked.
Return type:	bool
Returns:	bool True iff point collides with cell.

contains()¶

Check whether given point is contained in cell. This function is identical to the function collides(point).

Parameters:	Point & point (const) – The point to be checked.
Return type:	bool
Returns:	bool True iff point is contained in cell.

distance()¶

Compute distance to given point.

Parameters:	Point & point (const) – The point.
Return type:	double
Returns:	double The distance to the point.

facet_area()¶

Compute the area/length of given facet with respect to the cell

Parameters:	facet (std::size_t) – Index of the facet.
Return type:	double
Returns:	double Area/length of the facet.

get_cell_data()¶

Fill UFC cell with miscellaneous data.

Parameters:	& ufc_cell (ufc::cell) – local_facet (int) –
Return type:	void

get_cell_topology()¶

Fill UFC cell with topology data.

Parameters:	& ufc_cell (ufc::cell) –
Return type:	void

get_coordinate_dofs()¶

Get cell coordinate dofs (not vertex coordinates)

Parameters:	double > & coordinates (std::vector<) –
Return type:	void

get_vertex_coordinates()¶

Get cell vertex coordinates (not coordinate dofs)

Parameters:	double > & coordinates (std::vector<) –
Return type:	void

h()¶

Compute greatest distance between any two vertices

UnitSquareMesh mesh(1, 1);
Cell cell(mesh, 0);
info("%g", cell.h());

Return type:	double
Returns:	double The greatest distance between any two vertices of the cell.

inradius()¶

Compute inradius of cell

UnitSquareMesh mesh(1, 1);
Cell cell(mesh, 0);
info("%g", cell.inradius());

Return type:	double
Returns:	double Radius of the sphere inscribed in the cell.

intersection()¶

Compute triangulation of intersection with given entity

Parameters:	MeshEntity & entity (const) – The entity with which to intersect.
Return type:	std::vector< Point >
Returns:	std::vector<Point> A flattened array of simplices of dimension num_simplices x num_vertices x gdim = num_simplices x (tdim + 1) x gdim

normal()¶

Compute component i of normal of given facet with respect to the cell

Parameters:	facet (std::size_t) – Index of facet. i (std::size_t) – Component.
Return type:	double
Returns:	double Component i of the normal of the facet.

num_vertices()¶

Return number of vertices of cell.

Return type:	std::size_t

order()¶

Order entities locally

Parameters:	std::vector< std::int64_t > & local_to_global_vertex_indices (const) – The global vertex indices.
Return type:	void

ordered()¶

Check if entities are ordered

Parameters:	std::vector< std::int64_t > & local_to_global_vertex_indices (const) – The global vertex indices.
Return type:	bool
Returns:	bool True iff ordered.

orientation()¶

Compute orientation of cell

Return type:	std::size_t
Returns:	std::size_t Orientation of the cell (0 is ‘up’/’right’, 1 is ‘down’/’left’)

radius_ratio()¶

Compute ratio of inradius to circumradius times dim for cell. Useful as cell quality measure. Returns 1. for equilateral and 0. for degenerate cell. See Jonathan Richard Shewchuk: What Is a Good Linear Finite Element?, online: http://www.cs.berkeley.edu/~jrs/papers/elemj.pdf

UnitSquareMesh mesh(1, 1);
Cell cell(mesh, 0);
info("%g", cell.radius_ratio());

Return type:	double
Returns:	double topological_dimension * inradius / circumradius

squared_distance()¶

Compute squared distance to given point.

Parameters:	Point & point (const) – The point.
Return type:	double
Returns:	double The squared distance to the point.

thisown¶: The membership flag

type()¶

Return type of cell.

Return type:	CellType::Type

volume()¶

Compute (generalized) volume of cell

UnitSquare mesh(1, 1);
Cell cell(mesh, 0);
info("%g", cell.volume());

Return type:	double
Returns:	double The volume of the cell.