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Tpetra_Details_leftScaleLocalCrsMatrix.hpp
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41 
42 #ifndef TPETRA_DETAILS_LEFTSCALELOCALCRSMATRIX_HPP
43 #define TPETRA_DETAILS_LEFTSCALELOCALCRSMATRIX_HPP
44 
51 
52 #include "TpetraCore_config.h"
53 #include "Kokkos_Core.hpp"
54 #include "Kokkos_ArithTraits.hpp"
55 #include <type_traits>
56 
57 namespace Tpetra {
58 namespace Details {
59 
68 template<class LocalSparseMatrixType,
69  class ScalingFactorsViewType,
70  const bool divide>
72 public:
73  using val_type =
74  typename std::remove_const<typename LocalSparseMatrixType::value_type>::type;
75  using mag_type = typename ScalingFactorsViewType::non_const_value_type;
76  static_assert (ScalingFactorsViewType::Rank == 1,
77  "scalingFactors must be a rank-1 Kokkos::View.");
78  using device_type = typename LocalSparseMatrixType::device_type;
79 
88  LeftScaleLocalCrsMatrix (const LocalSparseMatrixType& A_lcl,
89  const ScalingFactorsViewType& scalingFactors,
90  const bool assumeSymmetric) :
91  A_lcl_ (A_lcl),
92  scalingFactors_ (scalingFactors),
93  assumeSymmetric_ (assumeSymmetric)
94  {}
95 
96  KOKKOS_INLINE_FUNCTION void
97  operator () (const typename LocalSparseMatrixType::ordinal_type lclRow) const
98  {
99  using LO = typename LocalSparseMatrixType::ordinal_type;
100  using KAM = Kokkos::ArithTraits<mag_type>;
101 
102  const mag_type curRowNorm = scalingFactors_(lclRow);
103  // Users are responsible for any divisions or multiplications by
104  // zero.
105  const mag_type scalingFactor = assumeSymmetric_ ?
106  KAM::sqrt (curRowNorm) : curRowNorm;
107  auto curRow = A_lcl_.row (lclRow);
108  const LO numEnt = curRow.length;
109  for (LO k = 0; k < numEnt; ++k) {
110  if (divide) { // constexpr, so should get compiled out
111  curRow.value (k) = curRow.value(k) / scalingFactor;
112  }
113  else {
114  curRow.value (k) = curRow.value(k) * scalingFactor;
115  }
116  }
117  }
118 
119 private:
120  LocalSparseMatrixType A_lcl_;
121  typename ScalingFactorsViewType::const_type scalingFactors_;
122  bool assumeSymmetric_;
123 };
124 
138 template<class LocalSparseMatrixType, class ScalingFactorsViewType>
139 void
140 leftScaleLocalCrsMatrix (const LocalSparseMatrixType& A_lcl,
141  const ScalingFactorsViewType& scalingFactors,
142  const bool assumeSymmetric,
143  const bool divide = true)
144 {
145  using device_type = typename LocalSparseMatrixType::device_type;
146  using execution_space = typename device_type::execution_space;
147  using LO = typename LocalSparseMatrixType::ordinal_type;
148  using range_type = Kokkos::RangePolicy<execution_space, LO>;
149 
150  const LO lclNumRows = A_lcl.numRows ();
151  if (divide) {
152  using functor_type =
153  LeftScaleLocalCrsMatrix<LocalSparseMatrixType,
154  typename ScalingFactorsViewType::const_type, true>;
155  functor_type functor (A_lcl, scalingFactors, assumeSymmetric);
156  Kokkos::parallel_for ("leftScaleLocalCrsMatrix",
157  range_type (0, lclNumRows), functor);
158  }
159  else {
160  using functor_type =
161  LeftScaleLocalCrsMatrix<LocalSparseMatrixType,
162  typename ScalingFactorsViewType::const_type, false>;
163  functor_type functor (A_lcl, scalingFactors, assumeSymmetric);
164  Kokkos::parallel_for ("leftScaleLocalCrsMatrix",
165  range_type (0, lclNumRows), functor);
166  }
167 }
168 
169 } // namespace Details
170 } // namespace Tpetra
171 
172 #endif // TPETRA_DETAILS_LEFTSCALELOCALCRSMATRIX_HPP
void leftScaleLocalCrsMatrix(const LocalSparseMatrixType &A_lcl, const ScalingFactorsViewType &scalingFactors, const bool assumeSymmetric, const bool divide=true)
Left-scale a KokkosSparse::CrsMatrix.
Kokkos::parallel_for functor that left-scales a KokkosSparse::CrsMatrix.
LeftScaleLocalCrsMatrix(const LocalSparseMatrixType &A_lcl, const ScalingFactorsViewType &scalingFactors, const bool assumeSymmetric)