Reference documentation for deal.II version Git a39983f358 2020-01-20 20:47:10 -0500
CellAccessor< dim, spacedim > Class Template Reference

#include <deal.II/grid/tria_accessor.h>

Inheritance diagram for CellAccessor< dim, spacedim >:
[legend]

## Public Types

using AccessorData = typename TriaAccessor< dim, dim, spacedim >::AccessorData

using Container = Triangulation< dim, spacedim >

Public Types inherited from TriaAccessor< dim, dim, spacedim >
using AccessorData = typename TriaAccessorBase< structdim, dim, spacedim >::AccessorData

Public Types inherited from TriaAccessorBase< structdim, dim, spacedim >
using LocalData = void *

## Public Member Functions

Constructors
CellAccessor (const Triangulation< dim, spacedim > *parent=nullptr, const int level=-1, const int index=-1, const AccessorData *local_data=nullptr)

CellAccessor (const TriaAccessor< dim, dim, spacedim > &cell_accessor)

template<int structdim2, int dim2, int spacedim2>
CellAccessor (const InvalidAccessor< structdim2, dim2, spacedim2 > &)

template<int structdim2, int dim2, int spacedim2>
CellAccessor (const TriaAccessor< structdim2, dim2, spacedim2 > &)

void operator= (const CellAccessor< dim, spacedim > &)=delete

Dealing with periodic neighbors
bool has_periodic_neighbor (const unsigned int i) const

TriaIterator< CellAccessor< dim, spacedim > > periodic_neighbor (const unsigned int i) const

TriaIterator< CellAccessor< dim, spacedim > > neighbor_or_periodic_neighbor (const unsigned int i) const

TriaIterator< CellAccessor< dim, spacedim > > periodic_neighbor_child_on_subface (const unsigned int face_no, const unsigned int subface_no) const

std::pair< unsigned int, unsigned int > periodic_neighbor_of_coarser_periodic_neighbor (const unsigned face_no) const

int periodic_neighbor_index (const unsigned int i) const

int periodic_neighbor_level (const unsigned int i) const

unsigned int periodic_neighbor_of_periodic_neighbor (const unsigned int i) const

unsigned int periodic_neighbor_face_no (const unsigned int i) const

bool periodic_neighbor_is_coarser (const unsigned int i) const

Dealing with boundary indicators
bool at_boundary (const unsigned int i) const

bool at_boundary () const

bool has_boundary_lines () const

Dealing with refinement indicators
RefinementCase< dim > refine_flag_set () const

void set_refine_flag (const RefinementCase< dim > ref_case=RefinementCase< dim >::isotropic_refinement) const

void clear_refine_flag () const

bool flag_for_face_refinement (const unsigned int face_no, const RefinementCase< dim - 1 > &face_refinement_case=RefinementCase< dim - 1 >::isotropic_refinement) const

bool flag_for_line_refinement (const unsigned int line_no) const

::internal::SubfaceCase< dim > subface_case (const unsigned int face_no) const

bool coarsen_flag_set () const

void set_coarsen_flag () const

void clear_coarsen_flag () const

Dealing with material indicators
types::material_id material_id () const

void set_material_id (const types::material_id new_material_id) const

void recursively_set_material_id (const types::material_id new_material_id) const

Dealing with subdomain indicators
types::subdomain_id subdomain_id () const

void set_subdomain_id (const types::subdomain_id new_subdomain_id) const

types::subdomain_id level_subdomain_id () const

void set_level_subdomain_id (const types::subdomain_id new_level_subdomain_id) const

void recursively_set_subdomain_id (const types::subdomain_id new_subdomain_id) const

Dealing with codim 1 cell orientation
bool direction_flag () const

unsigned int active_cell_index () const

int parent_index () const

TriaIterator< CellAccessor< dim, spacedim > > parent () const

Other functions
bool active () const

bool is_active () const

bool is_locally_owned () const

bool is_locally_owned_on_level () const

bool is_ghost () const

bool is_artificial () const

bool point_inside (const Point< spacedim > &p) const

void set_neighbor (const unsigned int i, const TriaIterator< CellAccessor< dim, spacedim >> &pointer) const

CellId id () const

Public Member Functions inherited from TriaAccessor< dim, dim, spacedim >
TriaAccessor (const Triangulation< dim, spacedim > *parent=nullptr, const int level=-1, const int index=-1, const AccessorData *local_data=nullptr)

TriaAccessor (const InvalidAccessor< structdim2, dim2, spacedim2 > &)

TriaAccessor (const TriaAccessor< structdim2, dim2, spacedim2 > &)

void operator= (const TriaAccessor &)=delete

bool used () const

double extent_in_direction (const unsigned int axis) const

double extent_in_direction (const unsigned int axis) const

double extent_in_direction (const unsigned int axis) const

TriaIterator< TriaAccessor< 0, dim, spacedim > > vertex_iterator (const unsigned int i) const

unsigned int vertex_index (const unsigned int i) const

Point< spacedim > & vertex (const unsigned int i) const

typename ::internal::TriangulationImplementation::Iterators< dim, spacedim >::line_iterator line (const unsigned int i) const

unsigned int line_index (const unsigned int i) const

typename ::internal::TriangulationImplementation::Iterators< dim, spacedim >::quad_iterator quad (const unsigned int i) const

unsigned int quad_index (const unsigned int i) const

bool face_orientation (const unsigned int face) const

bool face_flip (const unsigned int face) const

bool face_rotation (const unsigned int face) const

bool line_orientation (const unsigned int line) const

bool has_children () const

unsigned int n_children () const

unsigned int number_of_children () const

unsigned int max_refinement_depth () const

TriaIterator< TriaAccessor< structdim, dim, spacedim > > child (const unsigned int i) const

unsigned int child_iterator_to_index (const TriaIterator< TriaAccessor< structdim, dim, spacedim >> &child) const

TriaIterator< TriaAccessor< structdim, dim, spacedim > > isotropic_child (const unsigned int i) const

RefinementCase< structdim > refinement_case () const

int child_index (const unsigned int i) const

int isotropic_child_index (const unsigned int i) const

types::boundary_id boundary_id () const

void set_boundary_id (const types::boundary_id) const

void set_all_boundary_ids (const types::boundary_id) const

bool at_boundary () const

const Manifold< dim, spacedim > & get_manifold () const

types::manifold_id manifold_id () const

void set_manifold_id (const types::manifold_id) const

void set_all_manifold_ids (const types::manifold_id) const

bool user_flag_set () const

void set_user_flag () const

void clear_user_flag () const

void recursively_set_user_flag () const

void recursively_clear_user_flag () const

void clear_user_data () const

void set_user_pointer (void *p) const

void clear_user_pointer () const

void * user_pointer () const

void recursively_set_user_pointer (void *p) const

void recursively_clear_user_pointer () const

void set_user_index (const unsigned int p) const

void clear_user_index () const

unsigned int user_index () const

void recursively_set_user_index (const unsigned int p) const

void recursively_clear_user_index () const

double diameter () const

std::pair< Point< spacedim >, double > enclosing_ball () const

BoundingBox< spacedim > bounding_box () const

double extent_in_direction (const unsigned int axis) const

double minimum_vertex_distance () const

Point< spacedim > intermediate_point (const Point< structdim > &coordinates) const

Point< structdim > real_to_unit_cell_affine_approximation (const Point< spacedim > &point) const

Point< spacedim > center (const bool respect_manifold=false, const bool interpolate_from_surrounding=false) const

Point< spacedim > barycenter () const

double measure () const

bool is_translation_of (const TriaIterator< TriaAccessor< structdim, dim, spacedim >> &o) const

Public Member Functions inherited from TriaAccessorBase< structdim, dim, spacedim >
void operator= (const TriaAccessorBase *)=delete

int level () const

int index () const

IteratorState::IteratorStates state () const

const Triangulation< dim, spacedim > & get_triangulation () const

## Static Public Member Functions

static ::ExceptionBaseExcRefineCellNotActive ()

static ::ExceptionBaseExcCellFlaggedForRefinement ()

static ::ExceptionBaseExcCellFlaggedForCoarsening ()

## Protected Member Functions

unsigned int neighbor_of_neighbor_internal (const unsigned int neighbor) const

template<int dim_, int spacedim_>
bool point_inside_codim (const Point< spacedim_ > &p) const

Protected Member Functions inherited from TriaAccessorBase< structdim, dim, spacedim >
TriaAccessorBase (const Triangulation< dim, spacedim > *parent=nullptr, const int level=-1, const int index=-1, const AccessorData *=nullptr)

TriaAccessorBase (const TriaAccessorBase &)

void copy_from (const TriaAccessorBase &)

TriaAccessorBaseoperator= (const TriaAccessorBase &)

bool operator< (const TriaAccessorBase &other) const

bool operator== (const TriaAccessorBase &) const

bool operator!= (const TriaAccessorBase &) const

::internal::TriangulationImplementation::TriaObjects< ::internal::TriangulationImplementation::TriaObject< structdim > > & objects () const

void operator++ ()

void operator-- ()

## Private Member Functions

void set_active_cell_index (const unsigned int active_cell_index)

void set_parent (const unsigned int parent_index)

void set_direction_flag (const bool new_direction_flag) const

## Friends

template<int , int >
class Triangulation

## Accessing sub-objects and neighbors

TriaIterator< CellAccessor< dim, spacedim > > child (const unsigned int i) const

TriaIterator< TriaAccessor< dim - 1, dim, spacedim > > face (const unsigned int i) const

unsigned int face_iterator_to_index (const TriaIterator< TriaAccessor< dim - 1, dim, spacedim >> &face) const

std::array< TriaIterator< TriaAccessor< dim - 1, dim, spacedim > >, GeometryInfo< dim >::faces_per_cell > face_iterators () const

unsigned int face_index (const unsigned int i) const

TriaIterator< CellAccessor< dim, spacedim > > neighbor_child_on_subface (const unsigned int face_no, const unsigned int subface_no) const

TriaIterator< CellAccessor< dim, spacedim > > neighbor (const unsigned int i) const

int neighbor_index (const unsigned int i) const

int neighbor_level (const unsigned int i) const

unsigned int neighbor_of_neighbor (const unsigned int neighbor) const

bool neighbor_is_coarser (const unsigned int neighbor) const

std::pair< unsigned int, unsigned int > neighbor_of_coarser_neighbor (const unsigned int neighbor) const

unsigned int neighbor_face_no (const unsigned int neighbor) const

static bool is_level_cell ()

## Additional Inherited Members

Static Public Attributes inherited from TriaAccessorBase< structdim, dim, spacedim >
static const unsigned int space_dimension = spacedim

static const unsigned int dimension = dim

static const unsigned int structure_dimension = structdim

Protected Types inherited from TriaAccessorBase< structdim, dim, spacedim >
using AccessorData = void

Protected Attributes inherited from TriaAccessorBase< structdim, dim, spacedim >
typename ::internal::TriaAccessorImplementation::PresentLevelType< structdim, dim >::type present_level

int present_index

const Triangulation< dim, spacedim > * tria

## Detailed Description

### template<int dim, int spacedim = dim> class CellAccessor< dim, spacedim >

This class allows access to a cell: a line in one dimension, a quad in two dimension, etc.

The following refers to any dimension:

This class allows access to a cell, which is a line in 1D and a quad in 2D. Cells have more functionality than lines or quads by themselves, for example they can be flagged for refinement, they have neighbors, they have the possibility to check whether they are at the boundary etc. This class offers access to all this data.

Definition at line 2667 of file tria_accessor.h.

## ◆ AccessorData

template<int dim, int spacedim = dim>
 using CellAccessor< dim, spacedim >::AccessorData = typename TriaAccessor::AccessorData

Propagate the AccessorData type into the present class.

Definition at line 2673 of file tria_accessor.h.

## ◆ Container

template<int dim, int spacedim = dim>
 using CellAccessor< dim, spacedim >::Container = Triangulation

Define the type of the container this is part of.

Definition at line 2678 of file tria_accessor.h.

## ◆ CellAccessor() [1/4]

template<int dim, int spacedim = dim>
 CellAccessor< dim, spacedim >::CellAccessor ( const Triangulation< dim, spacedim > * parent = nullptr, const int level = -1, const int index = -1, const AccessorData * local_data = nullptr )

Constructor.

## ◆ CellAccessor() [2/4]

template<int dim, int spacedim = dim>
 CellAccessor< dim, spacedim >::CellAccessor ( const TriaAccessor< dim, dim, spacedim > & cell_accessor )

Copy constructor.

## ◆ CellAccessor() [3/4]

template<int dim, int spacedim>
template<int structdim2, int dim2, int spacedim2>
 CellAccessor< dim, spacedim >::CellAccessor ( const InvalidAccessor< structdim2, dim2, spacedim2 > & )

Conversion constructor. This constructor exists to make certain constructs simpler to write in dimension independent code. For example, it allows assigning a face iterator to a line iterator, an operation that is useful in 2d but doesn't make any sense in 3d. The constructor here exists for the purpose of making the code conform to C++ but it will unconditionally abort; in other words, assigning a face iterator to a line iterator is better put into an if-statement that checks that the dimension is two, and assign to a quad iterator in 3d (an operator that, without this constructor would be illegal if we happen to compile for 2d).

Definition at line 3683 of file tria_accessor.h.

## ◆ CellAccessor() [4/4]

template<int dim, int spacedim>
template<int structdim2, int dim2, int spacedim2>
 CellAccessor< dim, spacedim >::CellAccessor ( const TriaAccessor< structdim2, dim2, spacedim2 > & )

Another conversion operator between objects that don't make sense, just like the previous one.

Definition at line 3713 of file tria_accessor.h.

## ◆ operator=()

template<int dim, int spacedim = dim>
 void CellAccessor< dim, spacedim >::operator= ( const CellAccessor< dim, spacedim > & )
delete

Copy operator. These operators are usually used in a context like iterator a,b; *a=*b;. Presumably, the intent here is to copy the object pointed to by b to the object pointed to by a. However, the result of dereferencing an iterator is not an object but an accessor; consequently, this operation is not useful for iterators on triangulations. Consequently, this operator is declared as deleted and can not be used.

## ◆ child()

template<int dim, int spacedim = dim>
 TriaIterator > CellAccessor< dim, spacedim >::child ( const unsigned int i ) const

Return a pointer to the ith child. Overloaded version which returns a more reasonable iterator class.

## ◆ face()

template<int dim, int spacedim = dim>
 TriaIterator > CellAccessor< dim, spacedim >::face ( const unsigned int i ) const

Return an iterator to the ith face of this cell.

## ◆ face_iterator_to_index()

template<int dim, int spacedim = dim>
 unsigned int CellAccessor< dim, spacedim >::face_iterator_to_index ( const TriaIterator< TriaAccessor< dim - 1, dim, spacedim >> & face ) const

Return the face number of face on the current cell. This is the inverse function of TriaAccessor::face().

## ◆ face_iterators()

template<int dim, int spacedim = dim>
 std::array >, GeometryInfo::faces_per_cell> CellAccessor< dim, spacedim >::face_iterators ( ) const

Return an array of iterators to all faces of this cell.

## ◆ face_index()

template<int dim, int spacedim = dim>
 unsigned int CellAccessor< dim, spacedim >::face_index ( const unsigned int i ) const

Return the (global) index of the ith face of this cell.

Note
Despite the name, the index returned here is only global in the sense that it is specific to a particular Triangulation object or, in the case the triangulation is actually of type parallel::distributed::Triangulation, specific to that part of the distributed triangulation stored on the current processor.

## ◆ neighbor_child_on_subface()

template<int dim, int spacedim>
 TriaIterator< CellAccessor< dim, spacedim > > CellAccessor< dim, spacedim >::neighbor_child_on_subface ( const unsigned int face_no, const unsigned int subface_no ) const

Return an iterator to that cell that neighbors the present cell on the given face and subface number.

To succeed, the present cell must not be further refined, and the neighbor on the given face must be further refined exactly once; the returned cell is then a child of that neighbor.

The function may not be called in 1d, since there we have no subfaces. The implementation of this function is rather straightforward in 2d, by first determining which face of the neighbor cell the present cell is bordering on (this is what the neighbor_of_neighbor function does), and then asking GeometryInfo::child_cell_on_subface for the index of the child.

However, the situation is more complicated in 3d, since there faces may have more than one orientation, and we have to use face_orientation, face_flip and face_rotation for both this and the neighbor cell to figure out which cell we want to have.

This can lead to surprising results: if we are sitting on a cell and are asking for a cell behind subface sf, then this means that we are considering the subface for the face in the natural direction for the present cell. However, if the face as seen from this cell has face_orientation()==false, then the child of the face that separates the present cell from the neighboring cell's child is not necessarily the sf-th child of the face of this cell. This is so because the subface_no on a cell corresponds to the subface with respect to the intrinsic ordering of the present cell, whereas children of face iterators are computed with respect to the intrinsic ordering of faces; these two orderings are only identical if the face orientation is true, and reversed otherwise.

Similarly, effects of face_flip()==true and face_rotation()==true(), both of which indicate a non-standard face have to be considered.

Fortunately, this is only very rarely of concern, since usually one simply wishes to loop over all finer neighbors at a given face of an active cell. Only in the process of refinement of a Triangulation we want to set neighbor information for both our child cells and the neighbor's children. Since we can respect orientation of faces from our current cell in that case, we do NOT respect face_orientation, face_flip and face_rotation of the present cell within this function, i.e. the returned neighbor's child is behind subface subface concerning the intrinsic ordering of the given face.

Definition at line 2817 of file tria_accessor.cc.

## ◆ neighbor()

template<int dim, int spacedim = dim>
 TriaIterator > CellAccessor< dim, spacedim >::neighbor ( const unsigned int i ) const

Return a pointer to the ith neighbor. If the neighbor does not exist, i.e., if the ith face of the current object is at the boundary, then an invalid iterator is returned.

The neighbor of a cell has at most the same level as this cell. For example, consider the following situation:

Here, if you are on the top right cell and you ask for its left neighbor (which is, according to the conventions spelled out in the GeometryInfo class, its zeroth neighbor), then you will get the mother cell of the four small cells at the top left. In other words, the cell you get as neighbor has the same refinement level as the one you're on right now (the top right one) and it may have children.

On the other hand, if you were at the top right cell of the four small cells at the top left, and you asked for the right neighbor (which is associated with index i=1), then you would get the large cell at the top right which in this case has a lower refinement level and no children of its own.

## ◆ neighbor_index()

template<int dim, int spacedim = dim>
 int CellAccessor< dim, spacedim >::neighbor_index ( const unsigned int i ) const

Return the index of the ith neighbor. If the neighbor does not exist, its index is -1.

## ◆ neighbor_level()

template<int dim, int spacedim = dim>
 int CellAccessor< dim, spacedim >::neighbor_level ( const unsigned int i ) const

Return the level of the ith neighbor. If the neighbor does not exist, its level is -1.

## ◆ neighbor_of_neighbor()

template<int dim, int spacedim>
 unsigned int CellAccessor< dim, spacedim >::neighbor_of_neighbor ( const unsigned int neighbor ) const

Return the how-many'th neighbor this cell is of cell->neighbor(neighbor), i.e. return the face_no such that cell->neighbor(neighbor)->neighbor(face_no)==cell. This function is the right one if you want to know how to get back from a neighbor to the present cell.

Note that this operation is only useful if the neighbor is not coarser than the present cell. If the neighbor is coarser this function throws an exception. Use the neighbor_of_coarser_neighbor function in that case.

Definition at line 2256 of file tria_accessor.cc.

## ◆ neighbor_is_coarser()

template<int dim, int spacedim>
 bool CellAccessor< dim, spacedim >::neighbor_is_coarser ( const unsigned int neighbor ) const

Return, whether the neighbor is coarser then the present cell. This is important in case of ansiotropic refinement where this information does not depend on the levels of the cells.

Note, that in an anisotropic setting, a cell can only be coarser than another one at a given face, not on a general basis. The face of the finer cell is contained in the corresponding face of the coarser cell, the finer face is either a child or a grandchild of the coarser face.

Definition at line 2270 of file tria_accessor.cc.

## ◆ neighbor_of_coarser_neighbor()

template<int dim, int spacedim>
 std::pair< unsigned int, unsigned int > CellAccessor< dim, spacedim >::neighbor_of_coarser_neighbor ( const unsigned int neighbor ) const

This function is a generalization of the neighbor_of_neighbor function for the case of a coarser neighbor. It returns a pair of numbers, face_no and subface_no, with the following property, if the neighbor is not refined: cell->neighbor(neighbor)->neighbor_child_on_subface(face_no, subface_no)==cell. In 3D, a coarser neighbor can still be refined. In that case subface_no denotes the child index of the neighbors face that relates to our face: cell->neighbor(neighbor)->face(face_no)->child(subface_no)==cell->face(neighbor). This case in 3d and how it can happen is discussed in the introduction of the step-30 tutorial program.

This function is impossible for dim==1.

Definition at line 2281 of file tria_accessor.cc.

## ◆ neighbor_face_no()

template<int dim, int spacedim = dim>
 unsigned int CellAccessor< dim, spacedim >::neighbor_face_no ( const unsigned int neighbor ) const

This function is a generalization of the neighbor_of_neighbor and the neighbor_of_coarser_neighbor functions. It checks whether the neighbor is coarser or not and calls the respective function. In both cases, only the face_no is returned.

## ◆ is_level_cell()

template<int dim, int spacedim = dim>
 static bool CellAccessor< dim, spacedim >::is_level_cell ( )
static

Compatibility interface with DoFCellAccessor. Always returns false.

## ◆ has_periodic_neighbor()

template<int dim, int spacedim>
 bool CellAccessor< dim, spacedim >::has_periodic_neighbor ( const unsigned int i ) const

If the cell has a periodic neighbor at its ith face, this function returns true, otherwise, the returned value is false.

Definition at line 2461 of file tria_accessor.cc.

## ◆ periodic_neighbor()

template<int dim, int spacedim>
 TriaIterator< CellAccessor< dim, spacedim > > CellAccessor< dim, spacedim >::periodic_neighbor ( const unsigned int i ) const

For a cell with its ith face at a periodic boundary, see the entry for periodic boundaries, this function returns an iterator to the cell on the other side of the periodic boundary. If there is no periodic boundary at the ith face, an exception will be thrown. In order to avoid running into an exception, check the result of has_periodic_neighbor() for the ith face prior to using this function. The behavior of periodic_neighbor() is similar to neighbor(), in the sense that the returned cell has at most the same level of refinement as the current cell. On distributed meshes, by calling Triangulation::add_periodicity(), we can make sure that the element on the other side of the periodic boundary exists in this rank as a ghost cell or a locally owned cell.

Definition at line 2501 of file tria_accessor.cc.

## ◆ neighbor_or_periodic_neighbor()

template<int dim, int spacedim>
 TriaIterator< CellAccessor< dim, spacedim > > CellAccessor< dim, spacedim >::neighbor_or_periodic_neighbor ( const unsigned int i ) const

For a cell whose ith face is not at a boundary, this function returns the same result as neighbor(). If the ith face is at a periodic boundary this function returns the same result as periodic_neighbor(). If neither of the aforementioned conditions are met, i.e. the ith face is on a nonperiodic boundary, an exception will be thrown.

Definition at line 2530 of file tria_accessor.cc.

## ◆ periodic_neighbor_child_on_subface()

template<int dim, int spacedim>
 TriaIterator< CellAccessor< dim, spacedim > > CellAccessor< dim, spacedim >::periodic_neighbor_child_on_subface ( const unsigned int face_no, const unsigned int subface_no ) const

Return an iterator to the periodic neighbor of the cell at a given face and subface number. The general guidelines for using this function is similar to the function neighbor_child_on_subface(). The implementation of this function is consistent with periodic_neighbor_of_coarser_periodic_neighbor(). For instance, assume that we are sitting on a cell named cell1, whose neighbor behind the ith face is one level coarser. Let us name this coarser neighbor cell2. Then, by calling periodic_neighbor_of_coarser_periodic_neighbor(), from cell1, we get a face_num and a subface_num. Now, if we call periodic_neighbor_child_on_subface() from cell2, with the above face_num and subface_num, we get an iterator to cell1.

Definition at line 2547 of file tria_accessor.cc.

## ◆ periodic_neighbor_of_coarser_periodic_neighbor()

template<int dim, int spacedim = dim>
 std::pair< unsigned int, unsigned int > CellAccessor< dim, spacedim >::periodic_neighbor_of_coarser_periodic_neighbor ( const unsigned face_no ) const

This function is a generalization of periodic_neighbor_of_periodic_neighbor() for those cells which have a coarser periodic neighbor. The returned pair of numbers can be used in periodic_neighbor_child_on_subface() to get back to the current cell. In other words, the following assertion should be true, for a cell with coarser periodic neighbor: cell->periodic_neighbor(i)->periodic_neighbor_child_on_subface(face_no, subface_no)==cell

Definition at line 2601 of file tria_accessor.cc.

## ◆ periodic_neighbor_index()

template<int dim, int spacedim>
 int CellAccessor< dim, spacedim >::periodic_neighbor_index ( const unsigned int i ) const

This function returns the index of the periodic neighbor at the ith face of the current cell. If there is no periodic neighbor at the given face, the returned value is -1.

Definition at line 2666 of file tria_accessor.cc.

## ◆ periodic_neighbor_level()

template<int dim, int spacedim>
 int CellAccessor< dim, spacedim >::periodic_neighbor_level ( const unsigned int i ) const

This function returns the level of the periodic neighbor at the ith face of the current cell. If there is no periodic neighbor at the given face, the returned value is -1.

Definition at line 2676 of file tria_accessor.cc.

## ◆ periodic_neighbor_of_periodic_neighbor()

template<int dim, int spacedim>
 unsigned int CellAccessor< dim, spacedim >::periodic_neighbor_of_periodic_neighbor ( const unsigned int i ) const

For a cell with a periodic neighbor at its ith face, this function returns the face number of that periodic neighbor such that the current cell is the periodic neighbor of that neighbor. In other words the following assertion holds for those cells which have a periodic neighbor with the same or a higher level of refinement as the current cell: {cell->periodic_neighbor(i)-> periodic_neighbor(cell->periodic_neighbor_of_periodic_neighbor(i))==cell} For the cells with a coarser periodic neighbor, one should use periodic_neighbor_of_coarser_periodic_neighbor() and periodic_neighbor_child_on_subface() to get back to the current cell.

Definition at line 2686 of file tria_accessor.cc.

## ◆ periodic_neighbor_face_no()

template<int dim, int spacedim>
 unsigned int CellAccessor< dim, spacedim >::periodic_neighbor_face_no ( const unsigned int i ) const

If a cell has a periodic neighbor at its ith face, this function returns the face number of the periodic neighbor, which is connected to the ith face of this cell.

Definition at line 2696 of file tria_accessor.cc.

## ◆ periodic_neighbor_is_coarser()

template<int dim, int spacedim>
 bool CellAccessor< dim, spacedim >::periodic_neighbor_is_coarser ( const unsigned int i ) const

This function returns true if the element on the other side of the periodic boundary is coarser and returns false otherwise. The implementation allows this function to work in the case of anisotropic refinement.

Definition at line 2729 of file tria_accessor.cc.

## ◆ at_boundary() [1/2]

template<int dim, int spacedim>
 bool CellAccessor< dim, spacedim >::at_boundary ( const unsigned int i ) const

Return whether the ith vertex or face (depending on the dimension) is part of the boundary. This is true, if the ith neighbor does not exist.

Definition at line 2787 of file tria_accessor.cc.

## ◆ at_boundary() [2/2]

template<int dim, int spacedim>
 bool CellAccessor< dim, spacedim >::at_boundary ( ) const

Return whether the cell is at the boundary. Being at the boundary is defined by one face being on the boundary. Note that this does not catch cases where only one vertex of a quad or of a hex is at the boundary, or where only one line of a hex is at the boundary while the interiors of all faces are in the interior of the domain. For the latter case, the has_boundary_lines function is the right one to ask.

Definition at line 1910 of file tria_accessor.cc.

## ◆ has_boundary_lines()

template<int dim, int spacedim>
 bool CellAccessor< dim, spacedim >::has_boundary_lines ( ) const

This is a slight variation to the at_boundary function: for 1 and 2 dimensions, it is equivalent, for three dimensions it returns whether at least one of the 12 lines of the hexahedron is at a boundary. This, of course, includes the case where a whole face is at the boundary, but also some other cases.

Definition at line 2799 of file tria_accessor.cc.

## ◆ refine_flag_set()

template<int dim, int spacedim = dim>
 RefinementCase CellAccessor< dim, spacedim >::refine_flag_set ( ) const

Return the RefinementCase<dim> this cell was flagged to be refined with. The return value of this function can be compared to a bool to check if this cell is flagged for any kind of refinement. For example, if you have previously called cell->set_refine_flag() for a cell, then you will enter the 'if' block in the following snippet:

if (cell->refine_flag_set())
{
// yes, this cell is marked for refinement.
}

## ◆ set_refine_flag()

template<int dim, int spacedim = dim>
 void CellAccessor< dim, spacedim >::set_refine_flag ( const RefinementCase< dim > ref_case = RefinementCase< dim >::isotropic_refinement ) const

Flag the cell pointed to for refinement. This function is only allowed for active cells. Keeping the default value for ref_case will mark this cell for isotropic refinement.

If you choose anisotropic refinement, for example by passing as argument one of the flags RefinementCase::cut_x, RefinementCase::cut_y, RefinementCase::cut_z, or a combination of these, then keep in mind that refining in x-, y-, or z-direction happens with regard to the local coordinate system of the cell. In other words, these flags determine which edges and faces of the cell will be cut into new edges and faces. On the other hand, this process is independent of how the cell is oriented within the global coordinate system, and you should not assume any particular orientation of the cell's local coordinate system within the global coordinate system of the space it lives in.

## ◆ clear_refine_flag()

template<int dim, int spacedim = dim>
 void CellAccessor< dim, spacedim >::clear_refine_flag ( ) const

Clear the refinement flag.

## ◆ flag_for_face_refinement()

template<int dim, int spacedim = dim>
 bool CellAccessor< dim, spacedim >::flag_for_face_refinement ( const unsigned int face_no, const RefinementCase< dim - 1 > & face_refinement_case = RefinementCase< dim - 1 >::isotropic_refinement ) const

Modify the refinement flag of the cell to ensure (at least) the given refinement case face_refinement_case at face face_no, taking into account orientation, flip and rotation of the face. Return, whether the refinement flag had to be modified. This function is only allowed for active cells.

## ◆ flag_for_line_refinement()

template<int dim, int spacedim = dim>
 bool CellAccessor< dim, spacedim >::flag_for_line_refinement ( const unsigned int line_no ) const

Modify the refinement flag of the cell to ensure that line face_no will be refined. Return, whether the refinement flag had to be modified. This function is only allowed for active cells.

## ◆ subface_case()

template<int dim, int spacedim = dim>
 ::internal::SubfaceCase CellAccessor< dim, spacedim >::subface_case ( const unsigned int face_no ) const

Return the SubfaceCase of face face_no. Note that this is not identical to asking cell->face(face_no)->refinement_case() since the latter returns a RefinementCase<dim-1> and thus only considers one (anisotropic) refinement, whereas this function considers the complete refinement situation including possible refinement of the face's children. This function may only be called for active cells in 2d and 3d.

## ◆ coarsen_flag_set()

template<int dim, int spacedim = dim>
 bool CellAccessor< dim, spacedim >::coarsen_flag_set ( ) const

Return whether the coarsen flag is set or not.

## ◆ set_coarsen_flag()

template<int dim, int spacedim = dim>
 void CellAccessor< dim, spacedim >::set_coarsen_flag ( ) const

Flag the cell pointed to for coarsening. This function is only allowed for active cells.

## ◆ clear_coarsen_flag()

template<int dim, int spacedim = dim>
 void CellAccessor< dim, spacedim >::clear_coarsen_flag ( ) const

Clear the coarsen flag.

## ◆ material_id()

template<int dim, int spacedim>
 types::material_id CellAccessor< dim, spacedim >::material_id ( ) const

Return the material id of this cell.

For a typical use of this function, see the step-28 tutorial program.

Definition at line 1932 of file tria_accessor.cc.

## ◆ set_material_id()

template<int dim, int spacedim>
 void CellAccessor< dim, spacedim >::set_material_id ( const types::material_id new_material_id ) const

Set the material id of this cell.

For a typical use of this function, see the step-28 tutorial program.

Definition at line 1944 of file tria_accessor.cc.

## ◆ recursively_set_material_id()

template<int dim, int spacedim>
 void CellAccessor< dim, spacedim >::recursively_set_material_id ( const types::material_id new_material_id ) const

Set the material id of this cell and all its children (and grand- children, and so on) to the given value.

Definition at line 1958 of file tria_accessor.cc.

## ◆ subdomain_id()

template<int dim, int spacedim = dim>
 types::subdomain_id CellAccessor< dim, spacedim >::subdomain_id ( ) const

Return the subdomain id of this cell.

Note
The subdomain of a cell is a property only defined for active cells, i.e., cells that are not further refined. Consequently, you can only call this function if the cell it refers to has no children. For multigrid methods in parallel, it is also important to know which processor owns non-active cells, and for this you can call level_subdomain_id().

## ◆ set_subdomain_id()

template<int dim, int spacedim>
 void CellAccessor< dim, spacedim >::set_subdomain_id ( const types::subdomain_id new_subdomain_id ) const

Set the subdomain id of this cell.

See the glossary for more information. This function should not be called if you use a parallel::distributed::Triangulation object.

Note
The subdomain of a cell is a property only defined for active cells, i.e., cells that are not further refined. Consequently, you can only call this function if the cell it refers to has no children. For multigrid methods in parallel, it is also important to know which processor owns non-active cells, and for this you can call level_subdomain_id().

Definition at line 1972 of file tria_accessor.cc.

## ◆ level_subdomain_id()

template<int dim, int spacedim>
 types::subdomain_id CellAccessor< dim, spacedim >::level_subdomain_id ( ) const

Get the level subdomain id of this cell. This is used for parallel multigrid where not only the global mesh (consisting of the active cells) is partitioned among processors, but also the individual levels of the hierarchy of recursively refined cells that make up the mesh. In other words, the level subdomain id is a property that is also defined for non-active cells if a multigrid hierarchy is used.

Definition at line 1986 of file tria_accessor.cc.

## ◆ set_level_subdomain_id()

template<int dim, int spacedim>
 void CellAccessor< dim, spacedim >::set_level_subdomain_id ( const types::subdomain_id new_level_subdomain_id ) const

Set the level subdomain id of this cell. This is used for parallel multigrid.

Definition at line 1997 of file tria_accessor.cc.

## ◆ recursively_set_subdomain_id()

template<int dim, int spacedim>
 void CellAccessor< dim, spacedim >::recursively_set_subdomain_id ( const types::subdomain_id new_subdomain_id ) const

Set the subdomain id of this cell (if it is active) or all its terminal children (and grand-children, and so on, as long as they have no children of their own) to the given value. Since the subdomain id is a concept that is only defined for cells that are active (i.e., have no children of their own), this function only sets the subdomain ids for all children and grand children of this cell that are actually active, skipping intermediate child cells.

See the glossary for more information. This function should not be called if you use a parallel::distributed::Triangulation object since there the subdomain id is implicitly defined by which processor you're on.

Definition at line 2104 of file tria_accessor.cc.

## ◆ direction_flag()

template<int dim, int spacedim>
 bool CellAccessor< dim, spacedim >::direction_flag ( ) const

Return the orientation of this cell.

For the meaning of this flag, see GlossDirectionFlag.

Definition at line 2008 of file tria_accessor.cc.

## ◆ active_cell_index()

template<int dim, int spacedim>
 unsigned int CellAccessor< dim, spacedim >::active_cell_index ( ) const

Return the how many-th active cell the current cell is (assuming the current cell is indeed active). This is useful, for example, if you are accessing the elements of a vector with as many entries as there are active cells. Such vectors are used for estimating the error on each cell of a triangulation, for specifying refinement criteria passed to the functions in GridRefinement, and for generating cell-wise output.

The function throws an exception if the current cell is not active.

Note
If the triangulation this function is called on is of type parallel::distributed::Triangulation, then active cells may be locally owned, ghost cells, or artificial (see GlossLocallyOwnedCell, GlossGhostCell, and GlossArtificialCell). This function counts over all of them, including ghost and artificial active cells. This implies that the index returned by this function uniquely identifies a cell within the triangulation on a single processor, but does not uniquely identify the cell among the (parts of the) triangulation that is shared among processors. If you would like to identify active cells across processors, you need to consider the CellId of a cell returned by CellAccessor::id().

Definition at line 2079 of file tria_accessor.cc.

## ◆ parent_index()

template<int dim, int spacedim>
 int CellAccessor< dim, spacedim >::parent_index ( ) const

Return the index of the parent of this cell within the level of the triangulation to which the parent cell belongs. The level of the parent is of course one lower than that of the present cell. If the parent does not exist (i.e., if the object is at the coarsest level of the mesh hierarchy), an exception is generated.

Definition at line 2064 of file tria_accessor.cc.

## ◆ parent()

template<int dim, int spacedim>
 TriaIterator< CellAccessor< dim, spacedim > > CellAccessor< dim, spacedim >::parent ( ) const

Return an iterator to the parent. If the parent does not exist (i.e., if the object is at the coarsest level of the mesh hierarchy), an exception is generated.

Definition at line 2090 of file tria_accessor.cc.

## ◆ active()

template<int dim, int spacedim = dim>
 bool CellAccessor< dim, spacedim >::active ( ) const

Test that the cell has no children (this is the criterion for whether a cell is called "active").

Deprecated:
This function is deprecated. Use the is_active() function instead, which satisfies the naming scheme of other functions inquiring about yes/no properties of cells (e.g., is_ghost(), is_locally_owned(), etc.).

## ◆ is_active()

template<int dim, int spacedim = dim>
 bool CellAccessor< dim, spacedim >::is_active ( ) const

Test that the cell has no children (this is the criterion for whether a cell is called "active").

## ◆ is_locally_owned()

template<int dim, int spacedim = dim>
 bool CellAccessor< dim, spacedim >::is_locally_owned ( ) const

Return whether this cell is owned by the current processor or is owned by another processor. The function always returns true if applied to an object of type Triangulation, but may yield false if the triangulation is of type parallel::distributed::Triangulation.

See the glossary and the Parallel computing with multiple processors using distributed memory module for more information.

Postcondition
The returned value is equal to !is_ghost() && !is_artificial().
Note
Whether a cell is a ghost cell, artificial, or is locally owned or is a property that only pertains to cells that are active. Consequently, you can only call this function if the cell it refers to has no children.

## ◆ is_locally_owned_on_level()

template<int dim, int spacedim = dim>
 bool CellAccessor< dim, spacedim >::is_locally_owned_on_level ( ) const

Return true if either the Triangulation is not distributed or if level_subdomain_id() is equal to the id of the current processor.

## ◆ is_ghost()

template<int dim, int spacedim = dim>
 bool CellAccessor< dim, spacedim >::is_ghost ( ) const

Return whether this cell exists in the global mesh but (i) is owned by another processor, i.e. has a subdomain_id different from the one the current processor owns and (ii) is adjacent to a cell owned by the current processor.

This function only makes sense if the triangulation used is of kind parallel::distributed::Triangulation. In all other cases, the returned value is always false.

See the glossary and the Parallel computing with multiple processors using distributed memory module for more information.

Postcondition
The returned value is equal to !is_locally_owned() && !is_artificial().
Note
Whether a cell is a ghost cell, artificial, or is locally owned or is a property that only pertains to cells that are active. Consequently, you can only call this function if the cell it refers to has no children.

## ◆ is_artificial()

template<int dim, int spacedim = dim>
 bool CellAccessor< dim, spacedim >::is_artificial ( ) const

Return whether this cell is artificial, i.e. it isn't one of the cells owned by the current processor, and it also doesn't border on one. As a consequence, it exists in the mesh to ensure that each processor has all coarse mesh cells and that the 2:1 ratio of neighboring cells is maintained, but it is not one of the cells we should work on on the current processor. In particular, there is no guarantee that this cell isn't, in fact, further refined on one of the other processors.

This function only makes sense if the triangulation used is of kind parallel::distributed::Triangulation. In all other cases, the returned value is always false.

See the glossary and the Parallel computing with multiple processors using distributed memory module for more information.

Postcondition
The returned value is equal to !is_ghost() && !is_locally_owned().
Note
Whether a cell is a ghost cell, artificial, or is locally owned is a property that only pertains to cells that are active. Consequently, you can only call this function if the cell it refers to has no children.

## ◆ point_inside()

template<int dim, int spacedim = dim>
 bool CellAccessor< dim, spacedim >::point_inside ( const Point< spacedim > & p ) const

Test whether the point p is inside this cell. Points on the boundary are counted as being inside the cell.

Note that this function assumes that the mapping between unit cell and real cell is (bi-, tri-)linear, i.e. that faces in 2d and edges in 3d are straight lines. If you have higher order transformations, results may be different as to whether a point is in- or outside the cell in real space.

In case of codim>0, the point is first projected to the manifold where the cell is embedded and then check if this projection is inside the cell.

## ◆ set_neighbor()

template<int dim, int spacedim>
 void CellAccessor< dim, spacedim >::set_neighbor ( const unsigned int i, const TriaIterator< CellAccessor< dim, spacedim >> & pointer ) const

Set the neighbor i of this cell to the cell pointed to by pointer.

This function shouldn't really be public (but needs to for various reasons in order not to make a long list of functions friends): it modifies internal data structures and may leave things. Do not use it from application codes.

Definition at line 2118 of file tria_accessor.cc.

## ◆ id()

template<int dim, int spacedim>
 CellId CellAccessor< dim, spacedim >::id ( ) const

Return a unique ID for the current cell. This ID is constructed from the path in the hierarchy from the coarse father cell and works correctly in parallel computations using objects of type parallel::distributed::Triangulation. This function is therefore useful in providing a unique identifier for cells (active or not) that also works for parallel triangulations. See the documentation of the CellId class for more information.

Note
This operation takes O(level) time to compute. In most practical cases, the number of levels of a triangulation will depend logarithmically on the number of cells in the triangulation.

Definition at line 2148 of file tria_accessor.cc.

## ◆ neighbor_of_neighbor_internal()

template<int dim, int spacedim>
 unsigned int CellAccessor< dim, spacedim >::neighbor_of_neighbor_internal ( const unsigned int neighbor ) const
protected

This function assumes that the neighbor is not coarser than the current cell. In this case it returns the neighbor_of_neighbor() value. If, however, the neighbor is coarser this function returns an invalid_unsigned_int.

This function is not for public use. Use the function neighbor_of_neighbor() instead which throws an exception if called for a coarser neighbor. If neighbor is indeed coarser (you get to know this by e.g. the neighbor_is_coarser() function) then the neighbor_of_coarser_neighbor() function should be call. If you'd like to know only the face_no which is required to get back from the neighbor to the present cell then simply use the neighbor_face_no() function which can be used for coarser as well as non-coarser neighbors.

Definition at line 2189 of file tria_accessor.cc.

## ◆ point_inside_codim()

template<int dim, int spacedim>
template<int dim_, int spacedim_>
 bool CellAccessor< dim, spacedim >::point_inside_codim ( const Point< spacedim_ > & p ) const
protected

As for any codim>0 we can use a similar code and c++ does not allow partial templates. we use this auxiliary function that is then called from point_inside.

Definition at line 1871 of file tria_accessor.cc.

## ◆ set_active_cell_index()

template<int dim, int spacedim>
 void CellAccessor< dim, spacedim >::set_active_cell_index ( const unsigned int active_cell_index )
private

Set the active cell index of a cell. This is done at the end of refinement.

Definition at line 2039 of file tria_accessor.cc.

## ◆ set_parent()

template<int dim, int spacedim>
 void CellAccessor< dim, spacedim >::set_parent ( const unsigned int parent_index )
private

Set the parent of a cell.

Definition at line 2052 of file tria_accessor.cc.

## ◆ set_direction_flag()

template<int dim, int spacedim>
 void CellAccessor< dim, spacedim >::set_direction_flag ( const bool new_direction_flag ) const
private

Set the orientation of this cell.

For the meaning of this flag, see GlossDirectionFlag.

Definition at line 2022 of file tria_accessor.cc.

## ◆ Triangulation

template<int dim, int spacedim = dim>
template<int , int >
 friend class Triangulation
friend

Using directive for backwards-compatibility.

Deprecated:
Use TriangulationBase instead of Triangulation.

Definition at line 3641 of file tria_accessor.h.

The documentation for this class was generated from the following files: