42 #ifndef TPETRA_DETAILS_EXTRACTBLOCKDIAGONAL_HPP
43 #define TPETRA_DETAILS_EXTRACTBLOCKDIAGONAL_HPP
45 #include "TpetraCore_config.h"
46 #include "Tpetra_CrsMatrix.hpp"
47 #include "Teuchos_RCP.hpp"
61 template<
class SparseMatrixType,
62 class MultiVectorType>
63 void extractBlockDiagonal(
const SparseMatrixType& A, MultiVectorType & diagonal) {
64 using local_map_type =
typename SparseMatrixType::map_type::local_map_type;
65 using SC =
typename MultiVectorType::scalar_type;
66 using LO =
typename SparseMatrixType::local_ordinal_type;
67 using KCRS =
typename SparseMatrixType::local_matrix_device_type;
68 using lno_view_t =
typename KCRS::StaticCrsGraphType::row_map_type::const_type;
69 using lno_nnz_view_t =
typename KCRS::StaticCrsGraphType::entries_type::const_type;
70 using scalar_view_t =
typename KCRS::values_type::const_type;
71 using local_mv_type =
typename MultiVectorType::dual_view_type::t_dev;
72 using range_type = Kokkos::RangePolicy<typename SparseMatrixType::node_type::execution_space, LO>;
73 using ATS = Kokkos::ArithTraits<SC>;
74 using impl_ATS = Kokkos::ArithTraits<typename ATS::val_type>;
78 TEUCHOS_TEST_FOR_EXCEPTION(!A.getRowMap()->isSameAs(*diagonal.getMap()),
79 std::runtime_error,
"Tpetra::Details::extractBlockDiagonal was given incompatible maps");
82 LO numrows = diagonal.getLocalLength();
83 LO blocksize = diagonal.getNumVectors();
86 local_map_type rowmap = A.getRowMap()->getLocalMap();
87 local_map_type colmap = A.getRowMap()->getLocalMap();
88 local_mv_type diag = diagonal.getLocalViewDevice(Access::OverwriteAll);
89 const KCRS Amat = A.getLocalMatrixDevice();
90 lno_view_t Arowptr = Amat.graph.row_map;
91 lno_nnz_view_t Acolind = Amat.graph.entries;
92 scalar_view_t Avals = Amat.values;
94 Kokkos::parallel_for(
"Tpetra::extractBlockDiagonal",range_type(0,numrows),KOKKOS_LAMBDA(
const LO i){
95 LO diag_col = colmap.getLocalElement(rowmap.getGlobalElement(i));
96 LO blockStart = diag_col - (diag_col % blocksize);
97 LO blockStop = blockStart + blocksize;
98 for(LO k=0; k<blocksize; k++)
99 diag(i,k)=impl_ATS::zero();
101 for (
size_t k = Arowptr(i); k < Arowptr(i+1); k++) {
103 if (blockStart <= col && col < blockStop) {
104 diag(i,col-blockStart) = Avals(k);
113 #endif // TPETRA_DETAILS_EXTRACTBLOCKDIAGONAL_HPP
static bool debug()
Whether Tpetra is in debug mode.
Declaration of Tpetra::Details::Behavior, a class that describes Tpetra's behavior.