TriangulationDescription::Utilities Namespace Reference

Functions
template<int dim, int spacedim = dim>
Description< dim, spacedim >	create_description_from_triangulation (const ::Triangulation< dim, spacedim > &tria, const MPI_Comm comm, const TriangulationDescription::Settings settings=TriangulationDescription::Settings::default_setting, const unsigned int my_rank_in=numbers::invalid_unsigned_int)
template<int dim, int spacedim>
Description< dim, spacedim >	create_description_from_triangulation (const Triangulation< dim, spacedim > &tria, const LinearAlgebra::distributed::Vector< double, MemorySpace::Host > &partition, const TriangulationDescription::Settings settings=TriangulationDescription::Settings::default_setting)
template<int dim, int spacedim>
Description< dim, spacedim >	create_description_from_triangulation (const Triangulation< dim, spacedim > &tria, const LinearAlgebra::distributed::Vector< double, MemorySpace::Host > &partition, const std::vector< LinearAlgebra::distributed::Vector< double, MemorySpace::Host > > &mg_partitions, const TriangulationDescription::Settings settings=TriangulationDescription::Settings::default_setting)
template<int dim, int spacedim = dim>
Description< dim, spacedim >	create_description_from_triangulation_in_groups (const std::function< void(::Triangulation< dim, spacedim > &)> &serial_grid_generator, const std::function< void(::Triangulation< dim, spacedim > &, const MPI_Comm, const unsigned int)> &serial_grid_partitioner, const MPI_Comm comm, const int group_size=1, const typename Triangulation< dim, spacedim >::MeshSmoothing smoothing=::Triangulation< dim, spacedim >::none, const TriangulationDescription::Settings setting=TriangulationDescription::Settings::default_setting)
template<int dim, int spacedim>
Description< dim, spacedim >	create_description_from_triangulation (const Triangulation< dim, spacedim > &tria, const LinearAlgebra::distributed::Vector< double > &partition, const TriangulationDescription::Settings settings)
template<int dim, int spacedim>
Description< dim, spacedim >	create_description_from_triangulation (const Triangulation< dim, spacedim > &tria, const LinearAlgebra::distributed::Vector< double > &partition, const std::vector< LinearAlgebra::distributed::Vector< double > > &partitions_mg, const TriangulationDescription::Settings settings_in)

Detailed Description

A namespace for TriangulationDescription::Description utility functions.

Function Documentation

create_description_from_triangulation() [1/5]

template<int dim, int spacedim = dim>

Description< dim, spacedim > TriangulationDescription::Utilities::create_description_from_triangulation	(	const ::Triangulation< dim, spacedim > &	tria,
		const MPI_Comm	comm,
		const TriangulationDescription::Settings	settings = TriangulationDescription::Settings::default_setting,
		const unsigned int	my_rank_in = numbers::invalid_unsigned_int
	)

Construct TriangulationDescription::Description from a given partitioned triangulation tria and a specified process. The input triangulation can be either a serial triangulation of type Triangulation which has been colored (subdomain_id and/or level_subdomain_id has been set) or a distributed triangulation of type parallel::distributed::Triangulation, where the partitioning is adopted unaltered.

Example for a serial Triangulation:

Triangulation<dim, spacedim> tria_base;
 
// fill serial triangulation (e.g., read external mesh)
GridIn<dim, spacedim> grid_in;
grid_in.attach_triangulation(tria_base);
grid_in.read(file_name);
 
// partition serial triangulation
GridTools::partition_triangulation(
  Utilities::MPI::n_mpi_processes(comm), tria_base);
 
// create description
const TriangulationDescription::Description<dim, spacedim> description =
  TriangulationDescription::Utilities::
    create_description_from_triangulation(tria_base, comm);
 
// create triangulation
parallel::fullydistributed::Triangulation<dim, spacedim> tria_pft(comm);
tria_pft.create_triangulation(description);

Example for parallel::distributed::Triangulation (partitioning can be skipped, since the triangulation has already been partitioned by p4est):

parallel::distributed::Triangulation<dim, spacedim> tria_base(comm);
 
// fill tria_base (not shown)
 
// create triangulation
const TriangulationDescription::Description<dim, spacedim> description =
  TriangulationDescription::Utilities::
    create_description_from_triangulation(tria_base, comm);
 
// create triangulation
parallel::fullydistributed::Triangulation<dim, spacedim> tria_pft(comm);
tria_pft.create_triangulation(description);

Parameters

tria	Partitioned input triangulation.
comm	MPI_Communicator to be used. In the case of parallel::distributed::Triangulation, the communicators have to match.
settings	See the description of the Settings enumerator.
my_rank_in	Construct Description for the specified rank (only working for serial triangulations that have been partitioned by functions like GridTools::partition_triangulation()).

Returns

Description to be used to set up a Triangulation.

Note

If construct_multigrid_hierarchy is set in the settings, the source triangulation has to be set up with limit_level_difference_at_vertices.

Definition at line 726 of file tria_description.cc.

create_description_from_triangulation() [2/5]

template<int dim, int spacedim>

Description< dim, spacedim > TriangulationDescription::Utilities::create_description_from_triangulation	(	const Triangulation< dim, spacedim > &	tria,
		const LinearAlgebra::distributed::Vector< double, MemorySpace::Host > &	partition,
		const TriangulationDescription::Settings	settings = TriangulationDescription::Settings::default_setting
	)

Similar to the above function but the owner of active cells are provided by a cell vector (see also parallel::TriangulationBase::global_active_cell_index_partitioner() and CellAccessor::global_active_cell_index()). This function allows to repartition distributed Triangulation objects.

If the setup of multigrid levels is requested, they are partitioned according to a first-child policy.

Note

The communicator is extracted from the vector partition.

The triangulation tria can be set up on a subcommunicator of the communicator of partitioner. All processes that are not part of that subcommunicator need to set up the local triangulation with the special-purpose communicator MPI_COMM_NULL.

The multgrid levels are currently not constructed, since partition only describes the partitioning of the active level.

create_description_from_triangulation() [3/5]

template<int dim, int spacedim>

Description< dim, spacedim > TriangulationDescription::Utilities::create_description_from_triangulation	(	const Triangulation< dim, spacedim > &	tria,
		const LinearAlgebra::distributed::Vector< double, MemorySpace::Host > &	partition,
		const std::vector< LinearAlgebra::distributed::Vector< double, MemorySpace::Host > > &	mg_partitions,
		const TriangulationDescription::Settings	settings = TriangulationDescription::Settings::default_setting
	)

Similar to the above function but allowing the user to prescribe the partitioning of the multigrid levels.

create_description_from_triangulation_in_groups()

template<int dim, int spacedim = dim>

Description< dim, spacedim > TriangulationDescription::Utilities::create_description_from_triangulation_in_groups	(	const std::function< void(::Triangulation< dim, spacedim > &)> &	serial_grid_generator,
		const std::function< void(::Triangulation< dim, spacedim > &, const MPI_Comm, const unsigned int)> &	serial_grid_partitioner,
		const MPI_Comm	comm,
		const int	group_size = 1,
		const typename Triangulation< dim, spacedim >::MeshSmoothing	smoothing = ::Triangulation<dim, spacedim>::none,
		const TriangulationDescription::Settings	setting = TriangulationDescription::Settings::default_setting
	)

Construct a TriangulationDescription::Description. In contrast to the function above, this function is also responsible for creating a serial triangulation and for its partitioning (by calling the provided std::function objects). Internally only selected processes ( every n-th/each root of a group of size group_size) create a serial triangulation and the TriangulationDescription::Description for all processes in its group, which is communicated.

This function can also be used to read an external mesh only once (by the root process and a group consisting all processes). The following code snippet shows a modified version of the example provided in the documentation of create_description_from_triangulation(). Function calls that only need to be performed by the root process (read and partition mesh) have been moved into std::function objects.

// create and partition serial triangulation and create description
const TriangulationDescription::Description<dim, spacedim> description =
  TriangulationDescription::Utilities::
    create_description_from_triangulation_in_groups<dim, spacedim>(
      [file_name](auto &tria_base) {
        GridIn<dim, spacedim> grid_in;
        grid_in.attach_triangulation(tria_base);
        grid_in.read(file_name);
      },
      [](auto &tria_base, const auto comm, const auto group_size) {
        GridTools::partition_triangulation(
          Utilities::MPI::n_mpi_processes(comm), tria_base);
      },
      comm,
      Utilities::MPI::n_mpi_processes(comm));
 
// create triangulation
parallel::fullydistributed::Triangulation<dim, spacedim> tria_pft(comm);
tria_pft.create_triangulation(description);

Note

A reasonable group size is the size of a NUMA domain or the size of a compute node.

Parameters

serial_grid_generator	A function which creates a serial triangulation.
serial_grid_partitioner	A function which can partition a serial triangulation, i.e., sets the sudomain_ids of the active cells. The function takes as the first argument a serial triangulation, as the second argument the MPI communicator, and as the third argument the group size.
comm	MPI communicator.
group_size	The size of each group.
smoothing	Mesh smoothing type.
setting	See the description of the Settings enumerator.

Returns

Description to be used to set up a Triangulation.

Note

If construct_multigrid_hierarchy is set in the settings, the smoothing parameter is extended with the limit_level_difference_at_vertices flag.

Definition at line 790 of file tria_description.cc.

create_description_from_triangulation() [4/5]

template<int dim, int spacedim>

Description< dim, spacedim > TriangulationDescription::Utilities::create_description_from_triangulation	(	const Triangulation< dim, spacedim > &	tria,
		const LinearAlgebra::distributed::Vector< double > &	partition,
		const TriangulationDescription::Settings	settings
	)

Definition at line 920 of file tria_description.cc.

create_description_from_triangulation() [5/5]

template<int dim, int spacedim>

Description< dim, spacedim > TriangulationDescription::Utilities::create_description_from_triangulation	(	const Triangulation< dim, spacedim > &	tria,
		const LinearAlgebra::distributed::Vector< double > &	partition,
		const std::vector< LinearAlgebra::distributed::Vector< double > > &	partitions_mg,
		const TriangulationDescription::Settings	settings_in
	)

Definition at line 987 of file tria_description.cc.