Reference documentation for deal.II version Git d51799cb54 2020-09-28 09:22:08 +0200
deal.II and the C++11 standard

## Classes

class  IteratorRange< Iterator >

## Functions

template<typename FunctionObjectType >

template<typename FunctionObjectType >

template<typename BaseIterator , typename Predicate >
IteratorRange< FilteredIterator< BaseIterator > > filter_iterators (IteratorRange< BaseIterator > i, const Predicate &p)

template<typename BaseIterator , typename Predicate , typename... Targs>
IteratorRange< typename internal::FilteredIteratorImplementation::NestFilteredIterators< BaseIterator, std::tuple< Predicate, Targs... > >::type > filter_iterators (IteratorRange< BaseIterator > i, const Predicate &p, const Targs... args)

template<typename BaseIterator , typename Predicate >
IteratorRange< FilteredIterator< BaseIterator > > filter_iterators (IteratorRange< BaseIterator > i, const Predicate &p)

template<typename BaseIterator , typename Predicate , typename... Targs>
IteratorRange< typename internal::FilteredIteratorImplementation::NestFilteredIterators< BaseIterator, std::tuple< Predicate, Targs... > >::type > filter_iterators (IteratorRange< BaseIterator > i, const Predicate &p, const Targs... args)

## Cell iterator functions returning ranges of iterators

IteratorRange< cell_iteratorDoFHandler< dim, spacedim >::cell_iterators () const

IteratorRange< active_cell_iteratorDoFHandler< dim, spacedim >::active_cell_iterators () const

IteratorRange< level_cell_iteratorDoFHandler< dim, spacedim >::mg_cell_iterators () const

IteratorRange< cell_iteratorDoFHandler< dim, spacedim >::cell_iterators_on_level (const unsigned int level) const

IteratorRange< active_cell_iteratorDoFHandler< dim, spacedim >::active_cell_iterators_on_level (const unsigned int level) const

IteratorRange< level_cell_iteratorDoFHandler< dim, spacedim >::mg_cell_iterators_on_level (const unsigned int level) const

types::global_dof_index DoFHandler< dim, spacedim >::n_dofs () const

types::global_dof_index DoFHandler< dim, spacedim >::n_dofs (const unsigned int level) const

types::global_dof_index DoFHandler< dim, spacedim >::n_boundary_dofs () const

template<typename number >
types::global_dof_index DoFHandler< dim, spacedim >::n_boundary_dofs (const std::map< types::boundary_id, const Function< spacedim, number > *> &boundary_ids) const

types::global_dof_index DoFHandler< dim, spacedim >::n_boundary_dofs (const std::set< types::boundary_id > &boundary_ids) const

const BlockInfoDoFHandler< dim, spacedim >::block_info () const

types::global_dof_index DoFHandler< dim, spacedim >::n_locally_owned_dofs () const

const IndexSetDoFHandler< dim, spacedim >::locally_owned_dofs () const

const IndexSetDoFHandler< dim, spacedim >::locally_owned_mg_dofs (const unsigned int level) const

const std::vector< IndexSet > & DoFHandler< dim, spacedim >::locally_owned_dofs_per_processor () const

const std::vector< types::global_dof_index > & DoFHandler< dim, spacedim >::n_locally_owned_dofs_per_processor () const

const std::vector< IndexSet > & DoFHandler< dim, spacedim >::locally_owned_mg_dofs_per_processor (const unsigned int level) const

const FiniteElement< dim, spacedim > & DoFHandler< dim, spacedim >::get_fe (const unsigned int index=0) const

const hp::FECollection< dim, spacedim > & DoFHandler< dim, spacedim >::get_fe_collection () const

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

void DoFHandler< dim, spacedim >::prepare_for_serialization_of_active_fe_indices ()

void DoFHandler< dim, spacedim >::deserialize_active_fe_indices ()

virtual std::size_t DoFHandler< dim, spacedim >::memory_consumption () const

template<class Archive >
void DoFHandler< dim, spacedim >::save (Archive &ar, const unsigned int version) const

template<class Archive >
void DoFHandler< dim, spacedim >::load (Archive &ar, const unsigned int version)

template<class Archive >
void DoFHandler< dim, spacedim >::serialize (Archive &archive, const unsigned int version)

static ::ExceptionBaseDoFHandler< dim, spacedim >::ExcNoFESelected ()

static ::ExceptionBaseDoFHandler< dim, spacedim >::ExcInvalidBoundaryIndicator ()

static ::ExceptionBaseDoFHandler< dim, spacedim >::ExcInvalidLevel (int arg1)

static ::ExceptionBaseDoFHandler< dim, spacedim >::ExcNewNumbersNotConsecutive (types::global_dof_index arg1)

static ::ExceptionBaseDoFHandler< dim, spacedim >::ExcInvalidFEIndex (int arg1, int arg2)

static ::ExceptionBaseDoFHandler< dim, spacedim >::ExcNotAvailableWithoutHP ()

static ::ExceptionBaseDoFHandler< dim, spacedim >::ExcNotImplementedWithHP ()

## Cell iterator functions returning ranges of iterators

IteratorRange< cell_iteratorTriangulation< dim, spacedim >::cell_iterators () const

IteratorRange< active_cell_iteratorTriangulation< dim, spacedim >::active_cell_iterators () const

IteratorRange< cell_iteratorTriangulation< dim, spacedim >::cell_iterators_on_level (const unsigned int level) const

IteratorRange< active_cell_iteratorTriangulation< dim, spacedim >::active_cell_iterators_on_level (const unsigned int level) const

## Face iterator functions

IteratorRange< active_face_iteratorTriangulation< dim, spacedim >::active_face_iterators () const

## Detailed Description

Since version 9.0, deal.II requires a compiler that supports at least C++11. As part of this, many places in the internal implementation of deal.II are now using features that were only introduced in C++11. That said, deal.II also has functions and classes that make using it with C++11 features easier.

One example is support for C++11 range-based for loops. deal.II-based codes often have many loops of the kind

...
cell = triangulation.begin_active(),
endc = triangulation.end();
for (; cell!=endc; ++cell)
cell->set_refine_flag();

Using C++11's range-based for loops, you can now write this as follows:

...
for (auto &cell : triangulation.active_cell_iterators())
cell->set_refine_flag();

This relies on functions such as Triangulation::active_cell_iterators(), and equivalents in the DoF handler classes, DoFHandler::active_cell_iterators(), hp::DoFHandler::active_cell_iterators(). There are variants of these functions that provide iterator ranges for all cells (not just the active ones) and for cells on individual levels.

There are numerous other functions in the library that allow for the idiomatic use of range-based for loops. Examples are GeometryInfo::face_indices(), GeometryInfo::vertex_indices(), FEValuesBase::quadrature_point_indices(), among many others.

C++11 also introduces the concept of constexpr variables and function. The variables defined as constexpr are constant values that are computed during the compilation of the program and therefore have zero runtime cost associated with their initialization. Additionally, constexpr constants have properly defined lifetimes which prevent the so-called "static initialization order fiasco" completely. Functions can be marked as constexpr, indicating that they can produce compile-time constant return values if their input arguments are constant expressions. Additionally, classes with at least one constexpr constructor can be initialized as constexpr.

As an example, since the constructor Tensor::Tensor(const array_type &) is constexpr, we can initialize a tensor with an array during compile time as:

constexpr double[2][2] entries = {{1., 0.}, {0., 1.}};
constexpr Tensor<2, 2> A(entries);

Here, the contents of A are not stored on the stack. Rather, they are initialized during compile time and inserted into the .data portion of the executable program. The program can use these values at runtime without spending time for initialization. Initializing tensors can be simplified in one line.

constexpr Tensor<2, 2> A({{1., 0.}, {0., 1.}});

Some functions such as determinant() are specified as constexpr but they require a compiler with C++14 capability. As such, this function is internally declared as:

template <int dim, typename Number>

The macro DEAL_II_CONSTEXPR simplifies to constexpr if a C++14-capable compiler is available. Otherwise, for old compilers, it ignores DEAL_II_CONSTEXPR altogether. Therefore, with newer compilers, the user can write

constexpr double det_A = determinant(A);

assuming A is declared with the constexpr specifier. This example shows the performance gains of using constexpr because here we performed an operation with $$O(\text{dim}^3)$$ complexity during compile time, avoiding any runtime cost.

## Function Documentation

template<typename FunctionObjectType >
inline

Overload of the new_thread() function for objects that can be called like a function object without arguments. In particular, this function allows calling Threads::new_thread() with either objects that result from using std::bind, or using lambda functions. For example, this function is called when writing code such as

do_this();
then_do_that();
return 42;
});

Here, we run the sequence of functions do_this() and then_do_that() on a separate thread, by making the lambda function declared here the function to execute on the thread. The lambda function then returns 42 (which is a bit pointless here, but it could of course be some computed number), and this is going to be the returned value you can later retrieve via thread.return_value() once the thread (i.e., the body of the lambda function) has completed.

Note
Every lambda function (or whatever else it is you pass to the new_thread() function here, for example the result of a std::bind() expression) has a return type and consequently returns an object of this type. This type can be inferred using the C++11 decltype statement used in the declaration of this function, and it is then used as the template argument of the Threads::Thread object returned by the current function. In the example above, because the lambda function returns 42 (which in C++ has data type int), the inferred type is int and the task object will have type Task<int>. In other words, it is not necessary to explicitly specify in user code what that return type of the lambda or std::bind expression will be, though it is possible to explicitly do so by (entirely equivalently) writing
do_this();
then_do_that();
return 42;
});
In practice, the lambda functions you will pass to new_thread() will of course typically be more complicated. In particular, they will likely capture variables from the surrounding context and use them within the lambda. See https://en.wikipedia.org/wiki/Anonymous_function#C.2B.2B_.28since_C.2B.2B11.29 for more on how lambda functions work.
If you pass a lambda function as an argument to the current function that captures a variable by reference, or if you use a std::bind that binds a function argument to a reference variable using std::ref() or std::cref(), then obviously you can only do this if the variables you reference or capture have a lifetime that extends at least until the time where the thread finishes.

Definition at line 822 of file thread_management.h.

template<typename FunctionObjectType >
inline

Overload of the new_task function for objects that can be called like a function object without arguments. In particular, this function allows calling Threads::new_task() with either objects that result from using std::bind, or using lambda functions. For example, this function is called when writing code such as

do_this();
then_do_that();
return 42;
});

Here, we schedule the call to the sequence of functions do_this() and then_do_that() on a separate task, by making the lambda function declared here the function to execute on the task. The lambda function then returns 42 (which is a bit pointless here, but it could of course be some computed number), and this is going to be the returned value you can later retrieve via task.return_value() once the task (i.e., the body of the lambda function) has completed.

Note
When MultithreadInfo::n_threads() returns 1, i.e., if the deal.II runtime system has been configured to only use one thread, then this function just executes the given function object immediately and stores the return value in the Task object returned by this function.
Every lambda function (or whatever else it is you pass to the new_task() function here, for example the result of a std::bind() expression) has a return type and consequently returns an object of this type. This type can be inferred using the C++11 decltype statement used in the declaration of this function, and it is then used as the template argument of the Threads::Task object returned by the current function. In the example above, because the lambda function returns 42 (which in C++ has data type int), the inferred type is int and the task object will have type Task<int>. In other words, it is not necessary to explicitly specify in user code what that return type of the lambda or std::bind expression will be, though it is possible to explicitly do so by (entirely equivalently) writing
do_this();
then_do_that();
return 42;
});
In practice, the lambda functions you will pass to new_task() will of course typically be more complicated. In particular, they will likely capture variables from the surrounding context and use them within the lambda. See https://en.wikipedia.org/wiki/Anonymous_function#C.2B.2B_.28since_C.2B.2B11.29 for more on how lambda functions work.
If you pass a lambda function as an argument to the current function that captures a variable by reference, or if you use a std::bind that binds a function argument to a reference variable using std::ref() or std::cref(), then obviously you can only do this if the variables you reference or capture have a lifetime that extends at least until the time where the task finishes.
Threads::new_task() is, in essence, equivalent to calling std::async(std::launch::async, ...) in that it runs the given task in the background. (See https://en.cppreference.com/w/cpp/thread/async for more information.) The only difference is if you configured deal.II with DEAL_II_WITH_THREADS=OFF, then the operation described by the arguments of this function are executed immediately and the returned value is placed in the Task object returned here. This is useful for cases where one wants to run a program in a way where deal.II does not internally create parallel tasks, for example because one is already using one MPI process per core in a parallel computation.

Definition at line 1414 of file thread_management.h.

## ◆ cell_iterators() [1/2]

template<int dim, int spacedim>
 IteratorRange< typename DoFHandler< dim, spacedim >::cell_iterator > DoFHandler< dim, spacedim >::cell_iterators ( ) const

Return an iterator range that contains all cells (active or not) that make up this DoFHandler. Such a range is useful to initialize range-based for loops as supported by C++11. See the example in the documentation of active_cell_iterators().

Returns
The half open range [this->begin(), this->end())

Definition at line 2223 of file dof_handler.cc.

## ◆ active_cell_iterators() [1/2]

template<int dim, int spacedim>
 IteratorRange< typename DoFHandler< dim, spacedim >::active_cell_iterator > DoFHandler< dim, spacedim >::active_cell_iterators ( ) const

Return an iterator range that contains all active cells that make up this DoFHandler. Such a range is useful to initialize range-based for loops as supported by C++11, see also C++11 standard.

Range-based for loops are useful in that they require much less code than traditional loops (see here for a discussion of how they work). An example is that without range-based for loops, one often writes code such as the following:

DoFHandler<dim> dof_handler;
...
cell = dof_handler.begin_active(),
endc = dof_handler.end();
for (; cell!=endc; ++cell)
{
fe_values.reinit (cell);
...do the local integration on 'cell'...;
}

Using C++11's range-based for loops, this is now entirely equivalent to the following:

DoFHandler<dim> dof_handler;
...
for (const auto &cell : dof_handler.active_cell_iterators())
{
fe_values.reinit (cell);
...do the local integration on 'cell'...;
}
Returns
The half open range [this->begin_active(), this->end())

Definition at line 2233 of file dof_handler.cc.

## ◆ mg_cell_iterators()

template<int dim, int spacedim>
 IteratorRange< typename DoFHandler< dim, spacedim >::level_cell_iterator > DoFHandler< dim, spacedim >::mg_cell_iterators ( ) const

Return an iterator range that contains all cells (active or not) that make up this DoFHandler in their level-cell form. Such a range is useful to initialize range-based for loops as supported by C++11. See the example in the documentation of active_cell_iterators().

Returns
The half open range [this->begin_mg(), this->end_mg())

Definition at line 2244 of file dof_handler.cc.

## ◆ cell_iterators_on_level() [1/2]

template<int dim, int spacedim>
 IteratorRange< typename DoFHandler< dim, spacedim >::cell_iterator > DoFHandler< dim, spacedim >::cell_iterators_on_level ( const unsigned int level ) const

Return an iterator range that contains all cells (active or not) that make up the given level of this DoFHandler. Such a range is useful to initialize range-based for loops as supported by C++11. See the example in the documentation of active_cell_iterators().

Parameters
 [in] level A given level in the refinement hierarchy of this triangulation.
Returns
The half open range [this->begin(level), this->end(level))
Precondition
level must be less than this->n_levels().

Definition at line 2254 of file dof_handler.cc.

## ◆ active_cell_iterators_on_level() [1/2]

template<int dim, int spacedim>
 IteratorRange< typename DoFHandler< dim, spacedim >::active_cell_iterator > DoFHandler< dim, spacedim >::active_cell_iterators_on_level ( const unsigned int level ) const

Return an iterator range that contains all active cells that make up the given level of this DoFHandler. Such a range is useful to initialize range-based for loops as supported by C++11. See the example in the documentation of active_cell_iterators().

Parameters
 [in] level A given level in the refinement hierarchy of this triangulation.
Returns
The half open range [this->begin_active(level), this->end(level))
Precondition
level must be less than this->n_levels().

Definition at line 2265 of file dof_handler.cc.

## ◆ mg_cell_iterators_on_level()

template<int dim, int spacedim>
 IteratorRange< typename DoFHandler< dim, spacedim >::level_cell_iterator > DoFHandler< dim, spacedim >::mg_cell_iterators_on_level ( const unsigned int level ) const

Return an iterator range that contains all cells (active or not) that make up the given level of this DoFHandler in their level-cell form. Such a range is useful to initialize range-based for loops as supported by C++11. See the example in the documentation of active_cell_iterators().

Parameters
 [in] level A given level in the refinement hierarchy of this triangulation.
Returns
The half open range [this->begin_mg(level), this->end_mg(level))
Precondition
level must be less than this->n_levels().

Definition at line 2277 of file dof_handler.cc.

## ◆ filter_iterators() [1/4]

template<typename BaseIterator , typename Predicate >
 IteratorRange< FilteredIterator< BaseIterator > > filter_iterators ( IteratorRange< BaseIterator > i, const Predicate & p )

Filter the given range of iterators using a Predicate. This allows to replace:

DoFHandler<dim> dof_handler;
...
for (const auto &cell : dof_handler.active_cell_iterators())
{
if (cell->is_locally_owned())
{
fe_values.reinit (cell);
...do the local integration on 'cell'...;
}
}

by:

DoFHandler<dim> dof_handler;
...
const auto filtered_iterators_range =
for (const auto &cell : filtered_iterators_range)
{
fe_values.reinit (cell);
...do the local integration on 'cell'...;
}

Definition at line 860 of file filtered_iterator.h.

## ◆ filter_iterators() [2/4]

template<typename BaseIterator , typename Predicate , typename... Targs>
 IteratorRange< typename internal::FilteredIteratorImplementation::NestFilteredIterators< BaseIterator, std::tuple< Predicate, Targs... > >::type > filter_iterators ( IteratorRange< BaseIterator > i, const Predicate & p, const Targs... args )

Filter the given range of iterators through an arbitrary number of Predicates. This allows to replace:

DoFHandler<dim> dof_handler;
...
for (const auto &cell : dof_handler.active_cell_iterators())
{
if (cell->is_locally_owned())
{
if (cell->at_boundary())
{
fe_values.reinit (cell);
...do the local integration on 'cell'...;
}
}
}

by:

DoFHandler<dim> dof_handler;
...
const auto filtered_iterators_range =
for (const auto &cell : filter_iterators_range)
{
fe_values.reinit (cell);
...do the local integration on 'cell'...;
}

Definition at line 910 of file filtered_iterator.h.

## ◆ cell_iterators() [2/2]

template<int dim, int spacedim>
 IteratorRange< typename Triangulation< dim, spacedim >::cell_iterator > Triangulation< dim, spacedim >::cell_iterators ( ) const

Return an iterator range that contains all cells (active or not) that make up this triangulation. Such a range is useful to initialize range- based for loops as supported by C++11. See the example in the documentation of active_cell_iterators().

Returns
The half open range [this->begin(), this->end())

Definition at line 11301 of file tria.cc.

## ◆ active_cell_iterators() [2/2]

template<int dim, int spacedim>
 IteratorRange< typename Triangulation< dim, spacedim >::active_cell_iterator > Triangulation< dim, spacedim >::active_cell_iterators ( ) const

Return an iterator range that contains all active cells that make up this triangulation. Such a range is useful to initialize range-based for loops as supported by C++11, see also C++11 standard.

Range-based for loops are useful in that they require much less code than traditional loops (see here for a discussion of how they work). An example is that without range-based for loops, one often writes code such as the following (assuming for a moment that our goal is setting the user flag on every active cell):

...
cell = triangulation.begin_active(),
endc = triangulation.end();
for (; cell!=endc; ++cell)
cell->set_user_flag();

Using C++11's range-based for loops, this is now entirely equivalent to the following:

...
for (const auto &cell : triangulation.active_cell_iterators())
cell->set_user_flag();
Returns
The half open range [this->begin_active(), this->end())

Definition at line 11310 of file tria.cc.

## ◆ cell_iterators_on_level() [2/2]

template<int dim, int spacedim>
 IteratorRange< typename Triangulation< dim, spacedim >::cell_iterator > Triangulation< dim, spacedim >::cell_iterators_on_level ( const unsigned int level ) const

Return an iterator range that contains all cells (active or not) that make up the given level of this triangulation. Such a range is useful to initialize range-based for loops as supported by C++11. See the example in the documentation of active_cell_iterators().

Parameters
 [in] level A given level in the refinement hierarchy of this triangulation.
Returns
The half open range [this->begin(level), this->end(level))
Precondition
level must be less than this->n_levels().

Definition at line 11321 of file tria.cc.

## ◆ active_cell_iterators_on_level() [2/2]

template<int dim, int spacedim>
 IteratorRange< typename Triangulation< dim, spacedim >::active_cell_iterator > Triangulation< dim, spacedim >::active_cell_iterators_on_level ( const unsigned int level ) const

Return an iterator range that contains all active cells that make up the given level of this triangulation. Such a range is useful to initialize range-based for loops as supported by C++11. See the example in the documentation of active_cell_iterators().

Parameters
 [in] level A given level in the refinement hierarchy of this triangulation.
Returns
The half open range [this->begin_active(level), this->end(level))
Precondition
level must be less than this->n_levels().

Definition at line 11332 of file tria.cc.

## ◆ active_face_iterators()

template<int dim, int spacedim>
 IteratorRange< typename Triangulation< dim, spacedim >::active_face_iterator > Triangulation< dim, spacedim >::active_face_iterators ( ) const

Return an iterator range that contains all active faces that make up this triangulation. This function is the face version of Triangulation::active_cell_iterators(), and allows one to write code like, e.g.,

...
for (auto &face : triangulation.active_face_iterators())
face->set_manifold_id(42);
Returns
The half open range [this->begin_active_face(), this->end_face())

Definition at line 11409 of file tria.cc.

## ◆ filter_iterators() [3/4]

template<typename BaseIterator , typename Predicate >
 IteratorRange< FilteredIterator< BaseIterator > > filter_iterators ( IteratorRange< BaseIterator > i, const Predicate & p )
related

Filter the given range of iterators using a Predicate. This allows to replace:

DoFHandler<dim> dof_handler;
...
for (const auto &cell : dof_handler.active_cell_iterators())
{
if (cell->is_locally_owned())
{
fe_values.reinit (cell);
...do the local integration on 'cell'...;
}
}

by:

DoFHandler<dim> dof_handler;
...
const auto filtered_iterators_range =
for (const auto &cell : filtered_iterators_range)
{
fe_values.reinit (cell);
...do the local integration on 'cell'...;
}

Definition at line 860 of file filtered_iterator.h.

## ◆ filter_iterators() [4/4]

template<typename BaseIterator , typename Predicate , typename... Targs>
 IteratorRange< typename internal::FilteredIteratorImplementation::NestFilteredIterators< BaseIterator, std::tuple< Predicate, Targs... > >::type > filter_iterators ( IteratorRange< BaseIterator > i, const Predicate & p, const Targs... args )
related

Filter the given range of iterators through an arbitrary number of Predicates. This allows to replace:

DoFHandler<dim> dof_handler;
...
for (const auto &cell : dof_handler.active_cell_iterators())
{
if (cell->is_locally_owned())
{
if (cell->at_boundary())
{
fe_values.reinit (cell);
...do the local integration on 'cell'...;
}
}
}

by:

DoFHandler<dim> dof_handler;
...
const auto filtered_iterators_range =
for (const auto &cell : filter_iterators_range)
{
fe_values.reinit (cell);
...do the local integration on 'cell'...;
}

Definition at line 910 of file filtered_iterator.h.

## ◆ n_dofs() [1/2]

template<int dim, int spacedim = dim>
 types::global_dof_index DoFHandler< dim, spacedim >::n_dofs ( ) const

Return the global number of degrees of freedom. If the current object handles all degrees of freedom itself (even if you may intend to solve your linear system in parallel, such as in step-17 or step-18), then this number equals the number of locally owned degrees of freedom since this object doesn't know anything about what you want to do with it and believes that it owns every degree of freedom it knows about.

On the other hand, if this object operates on a parallel::distributed::Triangulation object, then this function returns the global number of degrees of freedom, accumulated over all processors.

In either case, included in the returned number are those DoFs which are constrained by hanging nodes, see Constraints on degrees of freedom.

Mathematically speaking, the number returned by this function equals the dimension of the finite element space (without taking into account constraints) that corresponds to (i) the mesh on which it is defined, and (ii) the finite element that is used by the current object. It also, of course, equals the number of shape functions that span this space.

## ◆ n_dofs() [2/2]

template<int dim, int spacedim = dim>
 types::global_dof_index DoFHandler< dim, spacedim >::n_dofs ( const unsigned int level ) const

The (global) number of multilevel degrees of freedom on a given level.

If no level degrees of freedom have been assigned to this level, returns numbers::invalid_dof_index. Else returns the number of degrees of freedom on this level.

## ◆ n_boundary_dofs() [1/3]

template<int dim, int spacedim>
 types::global_dof_index DoFHandler< dim, spacedim >::n_boundary_dofs ( ) const

Return the number of locally owned degrees of freedom located on the boundary.

Definition at line 2292 of file dof_handler.cc.

## ◆ n_boundary_dofs() [2/3]

template<int dim, int spacedim = dim>
template<typename number >
 types::global_dof_index DoFHandler< dim, spacedim >::n_boundary_dofs ( const std::map< types::boundary_id, const Function< spacedim, number > *> & boundary_ids ) const

Return the number of locally owned degrees of freedom located on those parts of the boundary which have a boundary indicator listed in the given set. The reason that a map rather than a set is used is the same as described in the documentation of that variant of DoFTools::make_boundary_sparsity_pattern() that takes a map.

There is, however, another overload of this function that takes a set argument (see below).

## ◆ n_boundary_dofs() [3/3]

template<int dim, int spacedim>
 types::global_dof_index DoFHandler< dim, spacedim >::n_boundary_dofs ( const std::set< types::boundary_id > & boundary_ids ) const

Return the number of degrees of freedom located on those parts of the boundary which have a boundary indicator listed in the given set. The

Definition at line 2341 of file dof_handler.cc.

## ◆ block_info()

template<int dim, int spacedim = dim>
 const BlockInfo& DoFHandler< dim, spacedim >::block_info ( ) const

Access to an object informing of the block structure of the dof handler.

If an FESystem is used in distribute_dofs(), degrees of freedom naturally split into several blocks. For each base element as many blocks appear as its multiplicity.

At the end of distribute_dofs(), the number of degrees of freedom in each block is counted, and stored in a BlockInfo object, which can be accessed here. If you have previously called distribute_mg_dofs(), the same is done on each level of the multigrid hierarchy. Additionally, the block structure on each cell can be generated in this object by calling initialize_local_block_info().

## ◆ n_locally_owned_dofs()

template<int dim, int spacedim = dim>
 types::global_dof_index DoFHandler< dim, spacedim >::n_locally_owned_dofs ( ) const

Return the number of degrees of freedom that belong to this process.

If this is a sequential DoFHandler, then the result equals that produced by n_dofs(). (Here, "sequential" means that either the whole program does not use MPI, or that it uses MPI but only uses a single MPI process, or that there are multiple MPI processes but the Triangulation on which this DoFHandler builds works only on one MPI process.) On the other hand, if we are operating on a parallel::distributed::Triangulation or parallel::shared::Triangulation, then it includes only the degrees of freedom that the current processor owns. Note that in this case this does not include all degrees of freedom that have been distributed on the current processor's image of the mesh: in particular, some of the degrees of freedom on the interface between the cells owned by this processor and cells owned by other processors may be theirs, and degrees of freedom on ghost cells are also not necessarily included.

## ◆ locally_owned_dofs()

template<int dim, int spacedim = dim>
 const IndexSet& DoFHandler< dim, spacedim >::locally_owned_dofs ( ) const

Return an IndexSet describing the set of locally owned DoFs as a subset of 0..n_dofs(). The number of elements of this set equals n_locally_owned_dofs().

## ◆ locally_owned_mg_dofs()

template<int dim, int spacedim = dim>
 const IndexSet& DoFHandler< dim, spacedim >::locally_owned_mg_dofs ( const unsigned int level ) const

Return an IndexSet describing the set of locally owned DoFs used for the given multigrid level as a subset of 0..n_dofs(level).

## ◆ locally_owned_dofs_per_processor()

template<int dim, int spacedim = dim>
 const std::vector& DoFHandler< dim, spacedim >::locally_owned_dofs_per_processor ( ) const

Return a vector that stores the locally owned DoFs of each processor.

## ◆ n_locally_owned_dofs_per_processor()

template<int dim, int spacedim = dim>
 const std::vector& DoFHandler< dim, spacedim >::n_locally_owned_dofs_per_processor ( ) const

Return a vector that stores the number of degrees of freedom each processor that participates in this triangulation owns locally. The sum of all these numbers equals the number of degrees of freedom that exist globally, i.e. what n_dofs() returns.

## ◆ locally_owned_mg_dofs_per_processor()

template<int dim, int spacedim = dim>
 const std::vector& DoFHandler< dim, spacedim >::locally_owned_mg_dofs_per_processor ( const unsigned int level ) const

Return a vector that stores the locally owned DoFs of each processor on the given level level.

## ◆ get_fe()

template<int dim, int spacedim = dim>
 const FiniteElement& DoFHandler< dim, spacedim >::get_fe ( const unsigned int index = 0 ) const

Return a constant reference to the selected finite element object. Since there is only one FiniteElement index must be equal to zero which is also the default value.

## ◆ get_fe_collection()

template<int dim, int spacedim = dim>
 const hp::FECollection& DoFHandler< dim, spacedim >::get_fe_collection ( ) const

Return a constant reference to the set of finite element objects that are used by this DoFHandler. Since this object only contains one FiniteElement, only this one object is returned wrapped in a hp::FECollection.

## ◆ get_triangulation()

template<int dim, int spacedim = dim>
 const Triangulation& DoFHandler< dim, spacedim >::get_triangulation ( ) const

Return a constant reference to the triangulation underlying this object.

## ◆ prepare_for_serialization_of_active_fe_indices()

template<int dim, int spacedim>
 void DoFHandler< dim, spacedim >::prepare_for_serialization_of_active_fe_indices ( )

Whenever serialization with a parallel::distributed::Triangulation as the underlying triangulation is considered, we also need to consider storing the active_fe_indices on all active cells as well.

This function registers that these indices are to be stored whenever the parallel::distributed::Triangulation::save() function is called on the underlying triangulation.

Note
Currently only implemented for triangulations of type parallel::distributed::Triangulation. An assertion will be triggered if a different type is registered.
The documentation of parallel::distributed::SolutionTransfer has further information on serialization.

Definition at line 3392 of file dof_handler.cc.

## ◆ deserialize_active_fe_indices()

template<int dim, int spacedim>
 void DoFHandler< dim, spacedim >::deserialize_active_fe_indices ( )

Whenever serialization with a parallel::distributed::Triangulation as the underlying triangulation is considered, we also need to consider storing the active_fe_indices on all active cells as well.

This function deserializes and distributes the previously stored active_fe_indices on all active cells.

Note
Currently only implemented for triangulations of type parallel::distributed::Triangulation. An assertion will be triggered if a different type is registered.
The documentation of parallel::distributed::SolutionTransfer has further information on serialization.

Definition at line 3478 of file dof_handler.cc.

## ◆ memory_consumption()

template<int dim, int spacedim>
 std::size_t DoFHandler< dim, spacedim >::memory_consumption ( ) const
virtual

Determine an estimate for the memory consumption (in bytes) of this object.

This function is made virtual, since a dof handler object might be accessed through a pointers to this base class, although the actual object might be a derived class.

Definition at line 2393 of file dof_handler.cc.

## ◆ save()

template<int dim, int spacedim = dim>
template<class Archive >
 void DoFHandler< dim, spacedim >::save ( Archive & ar, const unsigned int version ) const

Write the data of this object to a stream for the purpose of serialization.

template<int dim, int spacedim = dim>
template<class Archive >
 void DoFHandler< dim, spacedim >::load ( Archive & ar, const unsigned int version )

Read the data of this object from a stream for the purpose of serialization.

## ◆ serialize()

template<int dim, int spacedim = dim>
template<class Archive >
 void DoFHandler< dim, spacedim >::serialize ( Archive & archive, const unsigned int version )

Write and read the data of this object from a stream for the purpose of serialization.

## ◆ ExcNoFESelected()

template<int dim, int spacedim = dim>
 static ::ExceptionBase& DoFHandler< dim, spacedim >::ExcNoFESelected ( )
static

Exception

## ◆ ExcInvalidBoundaryIndicator()

template<int dim, int spacedim = dim>
 static ::ExceptionBase& DoFHandler< dim, spacedim >::ExcInvalidBoundaryIndicator ( )
static

Exception

## ◆ ExcInvalidLevel()

template<int dim, int spacedim = dim>
 static ::ExceptionBase& DoFHandler< dim, spacedim >::ExcInvalidLevel ( int arg1 )
static

Exception

Note
The message that will be printed by this exception reads:
<< "The given level " << arg1 << " is not in the valid range!"

## ◆ ExcNewNumbersNotConsecutive()

template<int dim, int spacedim = dim>
 static ::ExceptionBase& DoFHandler< dim, spacedim >::ExcNewNumbersNotConsecutive ( types::global_dof_index arg1 )
static

Exception

Note
The message that will be printed by this exception reads:
<< "The given list of new dof indices is not consecutive: " << "the index " << arg1 << " does not exist."

## ◆ ExcInvalidFEIndex()

template<int dim, int spacedim = dim>
 static ::ExceptionBase& DoFHandler< dim, spacedim >::ExcInvalidFEIndex ( int arg1, int arg2 )
static

Exception

Note
The message that will be printed by this exception reads:
<< "The mesh contains a cell with an active_fe_index of " << arg1 << ", but the finite element collection only has " << arg2 << " elements"

## ◆ ExcNotAvailableWithoutHP()

template<int dim, int spacedim = dim>
 static ::ExceptionBase& DoFHandler< dim, spacedim >::ExcNotAvailableWithoutHP ( )
static

Exception used when a certain feature doesn't make sense when DoFHandler does not hp capabilities.

Note
The message that will be printed by this exception reads:
"The current function doesn't make sense when used with a " "DoFHandler without hp capabilities."

## ◆ ExcNotImplementedWithHP()

template<int dim, int spacedim = dim>
 static ::ExceptionBase& DoFHandler< dim, spacedim >::ExcNotImplementedWithHP ( )
static

Exception used when a certain feature is not implemented when the DoFHandler has hp capabilities.

Note
The message that will be printed by this exception reads:
"The current function has not yet been implemented for a " "DoFHandler with hp capabilities."