MatrixCreator Namespace Reference

Functions
template<int dim, int spacedim, typename number >
void	create_mass_matrix (const Mapping< dim, spacedim > &mapping, const DoFHandler< dim, spacedim > &dof, const Quadrature< dim > &q, SparseMatrix< number > &matrix, const Function< spacedim, number > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim, typename number >
void	create_mass_matrix (const DoFHandler< dim, spacedim > &dof, const Quadrature< dim > &q, SparseMatrix< number > &matrix, const Function< spacedim, number > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim, typename number >
void	create_mass_matrix (const Mapping< dim, spacedim > &mapping, const DoFHandler< dim, spacedim > &dof, const Quadrature< dim > &q, SparseMatrix< typename numbers::NumberTraits< number >::real_type > &matrix, const Function< spacedim, number > &rhs, Vector< number > &rhs_vector, const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim, typename number >
void	create_mass_matrix (const DoFHandler< dim, spacedim > &dof, const Quadrature< dim > &q, SparseMatrix< typename numbers::NumberTraits< number >::real_type > &matrix, const Function< spacedim, number > &rhs, Vector< number > &rhs_vector, const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim, typename number >
void	create_mass_matrix (const hp::MappingCollection< dim, spacedim > &mapping, const hp::DoFHandler< dim, spacedim > &dof, const hp::QCollection< dim > &q, SparseMatrix< number > &matrix, const Function< spacedim, number > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim, typename number >
void	create_mass_matrix (const hp::DoFHandler< dim, spacedim > &dof, const hp::QCollection< dim > &q, SparseMatrix< number > &matrix, const Function< spacedim, number > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim, typename number >
void	create_mass_matrix (const hp::MappingCollection< dim, spacedim > &mapping, const hp::DoFHandler< dim, spacedim > &dof, const hp::QCollection< dim > &q, SparseMatrix< typename numbers::NumberTraits< number >::real_type > &matrix, const Function< spacedim, number > &rhs, Vector< number > &rhs_vector, const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim, typename number >
void	create_mass_matrix (const hp::DoFHandler< dim, spacedim > &dof, const hp::QCollection< dim > &q, SparseMatrix< typename numbers::NumberTraits< number >::real_type > &matrix, const Function< spacedim, number > &rhs, Vector< number > &rhs_vector, const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim, typename number >
void	create_boundary_mass_matrix (const Mapping< dim, spacedim > &mapping, const DoFHandler< dim, spacedim > &dof, const Quadrature< dim-1 > &q, SparseMatrix< typename numbers::NumberTraits< number >::real_type > &matrix, const std::map< types::boundary_id, const Function< spacedim, number > *> &boundary_functions, Vector< number > &rhs_vector, std::vector< types::global_dof_index > &dof_to_boundary_mapping, const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const weight=0, std::vector< unsigned int > component_mapping=std::vector< unsigned int >())
template<int dim, int spacedim, typename number >
void	create_boundary_mass_matrix (const DoFHandler< dim, spacedim > &dof, const Quadrature< dim-1 > &q, SparseMatrix< typename numbers::NumberTraits< number >::real_type > &matrix, const std::map< types::boundary_id, const Function< spacedim, number > *> &boundary_functions, Vector< number > &rhs_vector, std::vector< types::global_dof_index > &dof_to_boundary_mapping, const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const a=nullptr, std::vector< unsigned int > component_mapping=std::vector< unsigned int >())
template<int dim, int spacedim, typename number >
void	create_boundary_mass_matrix (const hp::MappingCollection< dim, spacedim > &mapping, const hp::DoFHandler< dim, spacedim > &dof, const hp::QCollection< dim-1 > &q, SparseMatrix< typename numbers::NumberTraits< number >::real_type > &matrix, const std::map< types::boundary_id, const Function< spacedim, number > *> &boundary_functions, Vector< number > &rhs_vector, std::vector< types::global_dof_index > &dof_to_boundary_mapping, const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const a=nullptr, std::vector< unsigned int > component_mapping=std::vector< unsigned int >())
template<int dim, int spacedim, typename number >
void	create_boundary_mass_matrix (const hp::DoFHandler< dim, spacedim > &dof, const hp::QCollection< dim-1 > &q, SparseMatrix< typename numbers::NumberTraits< number >::real_type > &matrix, const std::map< types::boundary_id, const Function< spacedim, number > *> &boundary_functions, Vector< number > &rhs_vector, std::vector< types::global_dof_index > &dof_to_boundary_mapping, const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const a=nullptr, std::vector< unsigned int > component_mapping=std::vector< unsigned int >())
template<int dim, int spacedim>
void	create_laplace_matrix (const Mapping< dim, spacedim > &mapping, const DoFHandler< dim, spacedim > &dof, const Quadrature< dim > &q, SparseMatrix< double > &matrix, const Function< spacedim > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim>
void	create_laplace_matrix (const DoFHandler< dim, spacedim > &dof, const Quadrature< dim > &q, SparseMatrix< double > &matrix, const Function< spacedim > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim>
void	create_laplace_matrix (const Mapping< dim, spacedim > &mapping, const DoFHandler< dim, spacedim > &dof, const Quadrature< dim > &q, SparseMatrix< double > &matrix, const Function< spacedim > &rhs, Vector< double > &rhs_vector, const Function< spacedim > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim>
void	create_laplace_matrix (const DoFHandler< dim, spacedim > &dof, const Quadrature< dim > &q, SparseMatrix< double > &matrix, const Function< spacedim > &rhs, Vector< double > &rhs_vector, const Function< spacedim > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim>
void	create_laplace_matrix (const hp::MappingCollection< dim, spacedim > &mapping, const hp::DoFHandler< dim, spacedim > &dof, const hp::QCollection< dim > &q, SparseMatrix< double > &matrix, const Function< spacedim > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim>
void	create_laplace_matrix (const hp::DoFHandler< dim, spacedim > &dof, const hp::QCollection< dim > &q, SparseMatrix< double > &matrix, const Function< spacedim > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim>
void	create_laplace_matrix (const hp::MappingCollection< dim, spacedim > &mapping, const hp::DoFHandler< dim, spacedim > &dof, const hp::QCollection< dim > &q, SparseMatrix< double > &matrix, const Function< spacedim > &rhs, Vector< double > &rhs_vector, const Function< spacedim > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
template<int dim, int spacedim>
void	create_laplace_matrix (const hp::DoFHandler< dim, spacedim > &dof, const hp::QCollection< dim > &q, SparseMatrix< double > &matrix, const Function< spacedim > &rhs, Vector< double > &rhs_vector, const Function< spacedim > *const a=nullptr, const ConstraintMatrix &constraints=ConstraintMatrix())
static ::ExceptionBase &	ExcComponentMismatch ()

Detailed Description

This namespace provides functions that assemble certain standard matrices for a given triangulation, using a given finite element, a given mapping and a quadrature formula.

Conventions for all functions

There exist two versions of almost all functions, one that takes an explicit Mapping argument and one that does not. The second one generally calls the first with an implicit \(Q_1\) argument (i.e., with an argument of kind MappingQGeneric(1)). If your intend your code to use a different mapping than a (bi-/tri-)linear one, then you need to call the functions with mapping argument should be used.

All functions take a sparse matrix object to hold the matrix to be created. The functions assume that the matrix is initialized with a sparsity pattern (SparsityPattern) corresponding to the given degree of freedom handler, i.e. the sparsity structure is already as needed. You can do this by calling the DoFTools::make_sparsity_pattern() function.

Furthermore it is assumed that no relevant data is in the matrix. Some entries will be overwritten and some others will contain invalid data if the matrix wasn't empty before. Therefore you may want to clear the matrix before assemblage.

By default, all created matrices are ‘raw’: they are not condensed, i.e. hanging nodes are not eliminated. The reason is that you may want to add several matrices and could then condense afterwards only once, instead of for every matrix. To actually do computations with these matrices, you have to condense the matrix using the ConstraintMatrix::condense function; you also have to condense the right hand side accordingly and distribute the solution afterwards. Alternatively, you can give an optional argument ConstraintMatrix that writes cell matrix (and vector) entries with distribute_local_to_global into the global matrix and vector. This way, adding several matrices from different sources is more complicated and you should make sure that you do not mix different ways of applying constraints. Particular caution is necessary when the given constraint matrix contains inhomogeneous constraints: In that case, the matrix assembled this way must be the only matrix (or you need to assemble the same right hand side for every matrix you generate and add together).

If you want to use boundary conditions with the matrices generated by the functions of this namespace in addition to the ones in a possible constraint matrix, you have to use a function like apply_boundary_values with the matrix, solution, and right hand side.

Supported matrices

At present there are functions to create the following matrices:

• create_mass_matrix: create the matrix with entries \(m_{ij} = \int_\Omega \phi_i(x) \phi_j(x) dx\) by numerical quadrature. Here, the \(\phi_i\) are the basis functions of the finite element space given.

  A coefficient may be given to evaluate \(m_{ij} = \int_\Omega a(x) \phi_i(x) \phi_j(x) dx\) instead.

• create_laplace_matrix: create the matrix with entries \(a_{ij} = \int_\Omega \nabla\phi_i(x) \nabla\phi_j(x) dx\) by numerical quadrature.

  Again, a coefficient may be given to evaluate \(a_{ij} = \int_\Omega a(x) \nabla\phi_i(x) \nabla\phi_j(x) dx\) instead.

Make sure that the order of the Quadrature formula given to these functions is sufficiently high to compute the matrices with the required accuracy. For the choice of this quadrature rule you need to take into account the polynomial degree of the FiniteElement basis functions, the roughness of the coefficient a, as well as the degree of the given Mapping (if any).

Note, that for vector-valued elements the mass matrix and the laplace matrix is implemented in such a way that each component couples only with itself, i.e. there is no coupling of shape functions belonging to different components. If the degrees of freedom have been sorted according to their vector component (e.g., using DoFRenumbering::component_wise()), then the resulting matrices will be block diagonal.

If the finite element for which the mass matrix or the Laplace matrix is to be built has more than one component, the functions accept a single coefficient as well as a vector valued coefficient function. For the latter case, the number of components must coincide with the number of components of the system finite element.

Matrices on the boundary

The create_boundary_mass_matrix() creates the matrix with entries \(m_{ij} = \int_{\Gamma} \phi_i \phi_j dx\), where \(\Gamma\) is the union of boundary parts with indicators contained in a std::map<types::boundary_id, const Function<spacedim,number>*> passed to the function (i.e. if you want to set up the mass matrix for the parts of the boundary with indicators zero and 2, you pass the function a map of unsigned chars as parameter boundary_functions containing the keys zero and 2). The size of the matrix is equal to the number of degrees of freedom that have support on the boundary, i.e. it is not a matrix on all degrees of freedom, but only a subset. (The \(\phi_i\) in the formula are the subset of basis functions which have at least part of their support on \(\Gamma\).) In order to determine which shape functions are to be considered, and in order to determine in which order, the function takes a dof_to_boundary_mapping; this object maps global DoF numbers to a numbering of the degrees of freedom located on the boundary, and can be obtained using the function DoFTools::map_dof_to_boundary_indices().

In order to work, the function needs a matrix of the correct size, built on top of a corresponding sparsity pattern. Since we only work on a subset of the degrees of freedom, we can't use the matrices and sparsity patterns that are created for the entire set of degrees of freedom. Rather, you should use the DoFHandler::make_boundary_sparsity_pattern() function to create the correct sparsity pattern, and build a matrix on top of it.

Note that at present there is no function that computes the mass matrix for all shape functions, though such a function would be trivial to implement.

Right hand sides

In many cases, you will not only want to build the matrix, but also a right hand side, which will give a vector with \(f_i = \int_\Omega f(x) \phi_i(x) dx\). For this purpose, each function exists in two versions, one only building the matrix and one also building the right hand side vector. If you want to create a right hand side vector without creating a matrix, you can use the VectorTools::create_right_hand_side() function. The use of the latter may be useful if you want to create many right hand side vectors.

Author

Wolfgang Bangerth, 1998, Ralf Hartmann, 2001

Function Documentation

create_mass_matrix() [1/8]

template<int dim, int spacedim, typename number >

void MatrixCreator::create_mass_matrix	(	const Mapping< dim, spacedim > &	mapping,
		const DoFHandler< dim, spacedim > &	dof,
		const Quadrature< dim > &	q,
		SparseMatrix< number > &	matrix,
		const Function< spacedim, number > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Assemble the mass matrix. If no coefficient is given (i.e., if the pointer to a function object is zero as it is by default), the coefficient is taken as being constant and equal to one. In case you want to specify constraints and use the default argument for the coefficient you have to specify the (unused) coefficient argument as (const Function<spacedim,number> *const)nullptr.

If the library is configured to use multithreading, this function works in parallel.

The optional argument constraints allows to apply constraints on the resulting matrix directly. Note, however, that this becomes difficult when you have inhomogeneous constraints and later want to add several such matrices, for example in time dependent settings such as the main loop of step-26.

See the general documentation of this namespace for more information.

create_mass_matrix() [2/8]

template<int dim, int spacedim, typename number >

void MatrixCreator::create_mass_matrix	(	const DoFHandler< dim, spacedim > &	dof,
		const Quadrature< dim > &	q,
		SparseMatrix< number > &	matrix,
		const Function< spacedim, number > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Call the create_mass_matrix() function, see above, with mapping=MappingQGeneric<dim>(1).

create_mass_matrix() [3/8]

template<int dim, int spacedim, typename number >

void MatrixCreator::create_mass_matrix	(	const Mapping< dim, spacedim > &	mapping,
		const DoFHandler< dim, spacedim > &	dof,
		const Quadrature< dim > &	q,
		SparseMatrix< typename numbers::NumberTraits< number >::real_type > &	matrix,
		const Function< spacedim, number > &	rhs,
		Vector< number > &	rhs_vector,
		const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Assemble the mass matrix and a right hand side vector. If no coefficient is given (i.e., if the pointer to a function object is zero as it is by default), the coefficient is taken as being constant and equal to one. In case you want to specify constraints and use the default argument for the coefficient you have to specify the (unused) coefficient argument as (const Function <spacedim,number> *const)nullptr.

If the library is configured to use multithreading, this function works in parallel.

The optional argument constraints allows to apply constraints on the resulting matrix directly. Note, however, that this becomes difficult when you have inhomogeneous constraints and later want to add several such matrices, for example in time dependent settings such as the main loop of step-26.

See the general documentation of this namespace for more information.

create_mass_matrix() [4/8]

template<int dim, int spacedim, typename number >

void MatrixCreator::create_mass_matrix	(	const DoFHandler< dim, spacedim > &	dof,
		const Quadrature< dim > &	q,
		SparseMatrix< typename numbers::NumberTraits< number >::real_type > &	matrix,
		const Function< spacedim, number > &	rhs,
		Vector< number > &	rhs_vector,
		const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Call the create_mass_matrix() function, see above, with mapping=MappingQGeneric<dim>(1).

create_mass_matrix() [5/8]

template<int dim, int spacedim, typename number >

void MatrixCreator::create_mass_matrix	(	const hp::MappingCollection< dim, spacedim > &	mapping,
		const hp::DoFHandler< dim, spacedim > &	dof,
		const hp::QCollection< dim > &	q,
		SparseMatrix< number > &	matrix,
		const Function< spacedim, number > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Same function as above, but for hp objects.

create_mass_matrix() [6/8]

template<int dim, int spacedim, typename number >

void MatrixCreator::create_mass_matrix	(	const hp::DoFHandler< dim, spacedim > &	dof,
		const hp::QCollection< dim > &	q,
		SparseMatrix< number > &	matrix,
		const Function< spacedim, number > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Same function as above, but for hp objects.

create_mass_matrix() [7/8]

template<int dim, int spacedim, typename number >

void MatrixCreator::create_mass_matrix	(	const hp::MappingCollection< dim, spacedim > &	mapping,
		const hp::DoFHandler< dim, spacedim > &	dof,
		const hp::QCollection< dim > &	q,
		SparseMatrix< typename numbers::NumberTraits< number >::real_type > &	matrix,
		const Function< spacedim, number > &	rhs,
		Vector< number > &	rhs_vector,
		const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Same function as above, but for hp objects.

create_mass_matrix() [8/8]

template<int dim, int spacedim, typename number >

void MatrixCreator::create_mass_matrix	(	const hp::DoFHandler< dim, spacedim > &	dof,
		const hp::QCollection< dim > &	q,
		SparseMatrix< typename numbers::NumberTraits< number >::real_type > &	matrix,
		const Function< spacedim, number > &	rhs,
		Vector< number > &	rhs_vector,
		const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Same function as above, but for hp objects.

create_boundary_mass_matrix() [1/4]

template<int dim, int spacedim, typename number >

void MatrixCreator::create_boundary_mass_matrix	(	const Mapping< dim, spacedim > &	mapping,
		const DoFHandler< dim, spacedim > &	dof,
		const Quadrature< dim-1 > &	q,
		SparseMatrix< typename numbers::NumberTraits< number >::real_type > &	matrix,
		const std::map< types::boundary_id, const Function< spacedim, number > *> &	boundary_functions,
		Vector< number > &	rhs_vector,
		std::vector< types::global_dof_index > &	dof_to_boundary_mapping,
		const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const	weight = 0,
		std::vector< unsigned int >	component_mapping = std::vector< unsigned int >()
	)

Assemble the mass matrix and a right hand side vector along the boundary.

The matrix is assumed to already be initialized with a suiting sparsity pattern (the DoFHandler provides an appropriate function).

If the library is configured to use multithreading, this function works in parallel.

• weight: an optional weight for the computation of the mass matrix. If no weight is given, it is set to one. In case you want to specify component_mapping and use the default argument for the coefficient you have to specify the (unused) coefficient argument as (const Function <spacedim,number> *const)nullptr.

• component_mapping: if the components in boundary_functions and dof do not coincide, this vector allows them to be remapped. If the vector is not empty, it has to have one entry for each component in dof. This entry is the component number in boundary_functions that should be used for this component in dof. By default, no remapping is applied.

Todo:

This function does not work for finite elements with cell-dependent shape functions.

create_boundary_mass_matrix() [2/4]

template<int dim, int spacedim, typename number >

void MatrixCreator::create_boundary_mass_matrix	(	const DoFHandler< dim, spacedim > &	dof,
		const Quadrature< dim-1 > &	q,
		SparseMatrix< typename numbers::NumberTraits< number >::real_type > &	matrix,
		const std::map< types::boundary_id, const Function< spacedim, number > *> &	boundary_functions,
		Vector< number > &	rhs_vector,
		std::vector< types::global_dof_index > &	dof_to_boundary_mapping,
		const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const	a = nullptr,
		std::vector< unsigned int >	component_mapping = std::vector< unsigned int >()
	)

Call the create_boundary_mass_matrix() function, see above, with mapping=MappingQGeneric<dim>(1).

create_boundary_mass_matrix() [3/4]

template<int dim, int spacedim, typename number >

void MatrixCreator::create_boundary_mass_matrix	(	const hp::MappingCollection< dim, spacedim > &	mapping,
		const hp::DoFHandler< dim, spacedim > &	dof,
		const hp::QCollection< dim-1 > &	q,
		SparseMatrix< typename numbers::NumberTraits< number >::real_type > &	matrix,
		const std::map< types::boundary_id, const Function< spacedim, number > *> &	boundary_functions,
		Vector< number > &	rhs_vector,
		std::vector< types::global_dof_index > &	dof_to_boundary_mapping,
		const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const	a = nullptr,
		std::vector< unsigned int >	component_mapping = std::vector< unsigned int >()
	)

Same function as above, but for hp objects.

create_boundary_mass_matrix() [4/4]

template<int dim, int spacedim, typename number >

void MatrixCreator::create_boundary_mass_matrix	(	const hp::DoFHandler< dim, spacedim > &	dof,
		const hp::QCollection< dim-1 > &	q,
		SparseMatrix< typename numbers::NumberTraits< number >::real_type > &	matrix,
		const std::map< types::boundary_id, const Function< spacedim, number > *> &	boundary_functions,
		Vector< number > &	rhs_vector,
		std::vector< types::global_dof_index > &	dof_to_boundary_mapping,
		const Function< spacedim, typename numbers::NumberTraits< number >::real_type > *const	a = nullptr,
		std::vector< unsigned int >	component_mapping = std::vector< unsigned int >()
	)

Same function as above, but for hp objects.

create_laplace_matrix() [1/8]

template<int dim, int spacedim>

void MatrixCreator::create_laplace_matrix	(	const Mapping< dim, spacedim > &	mapping,
		const DoFHandler< dim, spacedim > &	dof,
		const Quadrature< dim > &	q,
		SparseMatrix< double > &	matrix,
		const Function< spacedim > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Assemble the Laplace matrix. If no coefficient is given (i.e., if the pointer to a function object is zero as it is by default), the coefficient is taken as being constant and equal to one. In case you want to specify constraints and use the default argument for the coefficient you have to specify the (unused) coefficient argument as (const Function<spacedim> *const)nullptr.

If the library is configured to use multithreading, this function works in parallel.

The optional argument constraints allows to apply constraints on the resulting matrix directly. Note, however, that this becomes difficult when you have inhomogeneous constraints and later want to add several such matrices, for example in time dependent settings such as the main loop of step-26.

See the general documentation of this namespace for more information.

create_laplace_matrix() [2/8]

template<int dim, int spacedim>

void MatrixCreator::create_laplace_matrix	(	const DoFHandler< dim, spacedim > &	dof,
		const Quadrature< dim > &	q,
		SparseMatrix< double > &	matrix,
		const Function< spacedim > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Call the create_laplace_matrix() function, see above, with mapping=MappingQGeneric<dim>(1).

create_laplace_matrix() [3/8]

template<int dim, int spacedim>

void MatrixCreator::create_laplace_matrix	(	const Mapping< dim, spacedim > &	mapping,
		const DoFHandler< dim, spacedim > &	dof,
		const Quadrature< dim > &	q,
		SparseMatrix< double > &	matrix,
		const Function< spacedim > &	rhs,
		Vector< double > &	rhs_vector,
		const Function< spacedim > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Assemble the Laplace matrix and a right hand side vector. If no coefficient is given, it is assumed to be constant one. In case you want to specify constraints and use the default argument for the coefficient you have to specify the (unused) coefficient argument as (const Function<spacedim> *const)nullptr.

If the library is configured to use multithreading, this function works in parallel.

The optional argument constraints allows to apply constraints on the resulting matrix directly. Note, however, that this becomes difficult when you have inhomogeneous constraints and later want to add several such matrices, for example in time dependent settings such as the main loop of step-26.

See the general documentation of this namespace for more information.

create_laplace_matrix() [4/8]

template<int dim, int spacedim>

void MatrixCreator::create_laplace_matrix	(	const DoFHandler< dim, spacedim > &	dof,
		const Quadrature< dim > &	q,
		SparseMatrix< double > &	matrix,
		const Function< spacedim > &	rhs,
		Vector< double > &	rhs_vector,
		const Function< spacedim > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Call the create_laplace_matrix() function, see above, with mapping=MappingQGeneric<dim>(1).

create_laplace_matrix() [5/8]

template<int dim, int spacedim>

void MatrixCreator::create_laplace_matrix	(	const hp::MappingCollection< dim, spacedim > &	mapping,
		const hp::DoFHandler< dim, spacedim > &	dof,
		const hp::QCollection< dim > &	q,
		SparseMatrix< double > &	matrix,
		const Function< spacedim > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Like the functions above, but for hp dof handlers, mappings, and quadrature collections.

create_laplace_matrix() [6/8]

template<int dim, int spacedim>

void MatrixCreator::create_laplace_matrix	(	const hp::DoFHandler< dim, spacedim > &	dof,
		const hp::QCollection< dim > &	q,
		SparseMatrix< double > &	matrix,
		const Function< spacedim > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Like the functions above, but for hp dof handlers, mappings, and quadrature collections.

create_laplace_matrix() [7/8]

template<int dim, int spacedim>

void MatrixCreator::create_laplace_matrix	(	const hp::MappingCollection< dim, spacedim > &	mapping,
		const hp::DoFHandler< dim, spacedim > &	dof,
		const hp::QCollection< dim > &	q,
		SparseMatrix< double > &	matrix,
		const Function< spacedim > &	rhs,
		Vector< double > &	rhs_vector,
		const Function< spacedim > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Like the functions above, but for hp dof handlers, mappings, and quadrature collections.

create_laplace_matrix() [8/8]

template<int dim, int spacedim>

void MatrixCreator::create_laplace_matrix	(	const hp::DoFHandler< dim, spacedim > &	dof,
		const hp::QCollection< dim > &	q,
		SparseMatrix< double > &	matrix,
		const Function< spacedim > &	rhs,
		Vector< double > &	rhs_vector,
		const Function< spacedim > *const	a = nullptr,
		const ConstraintMatrix &	constraints = ConstraintMatrix()
	)

Like the functions above, but for hp dof handlers, mappings, and quadrature collections.