Dune::PDELab::NonOverlappingBorderDOFExchanger< GridOperator > Class Template Reference

Helper class for adding up matrix entries on border. More...

#include <dune/pdelab/gridoperator/common/borderdofexchanger.hh>

Classes
class	EntryAccumulator
	A DataHandle class to exchange matrix entries. More...
class	PatternExtender
	A DataHandle class to exchange matrix sparsity patterns. More...

Public Types
typedef std::unordered_map< typename GFSV::Ordering::Traits::DOFIndex, std::unordered_set< GlobalDOFIndex > >	BorderPattern
	Data structure for storing border-border matrix pattern entries in a communication-optimized form.

Public Member Functions
	NonOverlappingBorderDOFExchanger (const GridOperator &grid_operator)
	Constructor. Sets up the local to global relations. More...
void	accumulateBorderEntries (const GridOperator &grid_operator, Matrix &matrix)
	Sums up the entries corresponding to border vertices. More...

Detailed Description

template<typename GridOperator>
class Dune::PDELab::NonOverlappingBorderDOFExchanger< GridOperator >

Helper class for adding up matrix entries on border.

Utility class for accumulating matrix entries for border-border couplings in parallel computations with nonoverlapping domain decomposition.

For nonoverlapping grids, there is an additional problem related to matrix entries that should exist on a given node, but which are only present on a remote node. For these entries, we not only need to accumulate the matrix values, we also have to create those matrix entries in the sparsity pattern, as they cannot be discovered during the node-local matrix creation:

We look at a 2D example with a nonoverlapping grid, two processes and no ghosts with Q1 discretization. Process 0 has the left part of the domain with three cells and eight vertices (1-8), Process 1 the right part with three cells and eight vertices (2,4,7-12).

 1 _ 2        2 _ 9 _ 10
 |   |        |   |   |
 3 _ 4 _ 7    4 _ 7 _ 11
 |   |   |        |   |
 5 _ 6 _ 8        8 _ 12
 

If we look at vertex 7 and the corresponding entries in the matrix for P0, there will be entries for (7,4) and (7,8), but not for (7,2). Unfortunately, local pattern creation will not create the link (7,2) on process 0. This class will find this kind of entry and extend the sparsity pattern appropriately.

Template Parameters

GridOperator

The grid operator to work on.

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

• dune/pdelab/gridoperator/common/borderdofexchanger.hh