Entity Set Partitions

Handles the partitioning over a set of entities (e.g. a grid view)

Handles the partitioning over a set of entities (e.g. a grid view)

Overview

The partition is defined as three nested containers that reflect the structure of the partition. The first and outermost partition is a container of LabelSets. Each LabelSet is a container of PatchSets, finally, a PatchSet is a container of grid entities. The partition is non-overlapping, meaning that every entity of the entity set is present in the partition but not repeated.

Label sets

For a given halo distance N, entities within a label set have the guarantee to not be connected to any other label entity within at-most N edges on the grid hyper-graph.

Halo Region

For a given halo distance N, the halo overlap of the entity set refers to the entities connected to any other patch in the same label set within at at-most N edges on the grid hyper-graph. Other entities are consireded to be in the halo interior. Among others, the halo overlap helps to determine computation regions that are shared with another patch of the same label (e.g., for concurrent computations).

Coloring

When more than one label is present in the partition and all entities are in the halo interior, we say that the partition is colored. Partitions providing this guarantee are Dune::PDELab::EntitySetPartition::MetisColored and Dune::PDELab::EntitySetPartition::IteratorSplitColored.

Usage

Partitions in this group allow to have colored and uncolored partitions parameterized by the halo distance and number of total patches. The halo distance is specified at construction of the partition and is a problem dependent requirement. For example, conforming grids with only volume integrals typically need a halo distance equal to 0 (e.g., due to shared vertices).

using GridView = /*...*/;
GridView gv = /*...*/;
Dune::PDELab::EntitySetPartition::MetisColored<GridView> partition(gv);
 
for(const auto& labelSet : partition)
  for(const auto& patchSet : partition) // maybe multi-threaded
    for(const auto& entity : patchSet)
      /* do entity operation */;