Ifpack2 Templated Preconditioning Package  Version 1.0
Ifpack2_LinePartitioner_decl.hpp
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42 
43 #ifndef IFPACK2_LINEPARTITIONER_DECL_HPP
44 #define IFPACK2_LINEPARTITIONER_DECL_HPP
45 
46 #include "Ifpack2_ConfigDefs.hpp"
47 #include "Ifpack2_OverlappingPartitioner.hpp"
48 #include "Tpetra_MultiVector.hpp"
49 
50 namespace Ifpack2 {
51 
53 /* \brief Ifpack2::LinePartitioner: A class to define partitions into a set of lines.
54 
55 These "line" partitions could then be used in to do block Gauss-Seidel smoothing, for instance.
56 
57 The current implementation uses a local line detection inspired by the work of Mavriplis
58 for convection-diffusion (AIAA Journal, Vol 37(10), 1999).
59 
60 Here we use coordinate information to pick "close" points if they are sufficiently far away
61 from the "far" points. We also make sure the line can never double back on itself, so that
62 the associated sub-matrix could (in theory) be handed off to a fast triangular solver. This
63 implementation doesn't actual do that, however.
64 
65 This implementation is deived from the related routine in ML.
66 
67 Supported parameters:
68  \c "partitioner: line detection threshold": if ||x_j - x_i||^2 < thresh * max_k||x_k - x_i||^2, then the points are close enough to line smooth <Scalar>
69  \c "partitioner: coordinates" : coordinates of local nodes < Teuchos::MultiVector<Scalar> >
70  \c "partitioner: PDE equations": number of equations per node <int>
71 */
73 
74  template<class GraphType,class Scalar>
75 class LinePartitioner : public OverlappingPartitioner<GraphType> {
76 public:
77  typedef typename GraphType::local_ordinal_type local_ordinal_type;
78  typedef typename GraphType::global_ordinal_type global_ordinal_type;
79  typedef typename GraphType::node_type node_type;
80  typedef Tpetra::RowGraph<local_ordinal_type, global_ordinal_type, node_type> row_graph_type;
81  typedef Tpetra::MultiVector<Scalar,local_ordinal_type, global_ordinal_type, node_type> multivector_type;
82  typedef typename Teuchos::ScalarTraits<Scalar>::magnitudeType MT;
83 
84 
86  LinePartitioner(const Teuchos::RCP<const row_graph_type>& graph);
87 
89  virtual ~LinePartitioner();
90 
92  void setPartitionParameters(Teuchos::ParameterList& List);
93 
95  void computePartitions();
96 
97 private:
98  // Useful functions
99  int Compute_Blocks_AutoLine(Teuchos::ArrayView<local_ordinal_type> blockIndices) const;
100  void local_automatic_line_search(int NumEqns, Teuchos::ArrayView <local_ordinal_type> blockIndices, local_ordinal_type last, local_ordinal_type next, local_ordinal_type LineID, MT tol, Teuchos::Array<local_ordinal_type> itemp, Teuchos::Array<MT> dtemp) const;
101 
102 
103 
104  // User data
105  int NumEqns_;
106  Teuchos::RCP<multivector_type> coord_;
107  MT threshold_;
108 
109 };
110 
111 }// namespace Ifpack2
112 
113 #endif // IFPACK2_LINEPARTITIONER_DECL_HPP
LinePartitioner(const Teuchos::RCP< const row_graph_type > &graph)
Constructor.
Definition: Ifpack2_LinePartitioner_def.hpp:60
void computePartitions()
Compute the partitions.
Definition: Ifpack2_LinePartitioner_def.hpp:86
virtual ~LinePartitioner()
Destructor.
Definition: Ifpack2_LinePartitioner_def.hpp:66
Definition: Ifpack2_OverlappingPartitioner_decl.hpp:77
void setPartitionParameters(Teuchos::ParameterList &List)
Set the partitioner&#39;s parameters (none for linear partitioning).
Definition: Ifpack2_LinePartitioner_def.hpp:72
Preconditioners and smoothers for Tpetra sparse matrices.
Definition: Ifpack2_AdditiveSchwarz_decl.hpp:72
Definition: Ifpack2_LinePartitioner_decl.hpp:75