Tpetra parallel linear algebra Version of the Day
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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
57namespace Tpetra {
58namespace Details {
59
68template<class LocalSparseMatrixType,
69 class ScalingFactorsViewType,
70 const bool divide>
72public:
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
90 const bool assumeSymmetric) :
91 A_lcl_ (A_lcl),
92 scalingFactors_ (scalingFactors),
93 assumeSymmetric_ (assumeSymmetric)
94 {}
95
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
119private:
120 LocalSparseMatrixType A_lcl_;
121 typename ScalingFactorsViewType::const_type scalingFactors_;
122 bool assumeSymmetric_;
123};
124
138template<class LocalSparseMatrixType, class ScalingFactorsViewType>
139void
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 =
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 =
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
Struct that holds views of the contents of a CrsMatrix.
Kokkos::parallel_for functor that left-scales a KokkosSparse::CrsMatrix.
LeftScaleLocalCrsMatrix(const LocalSparseMatrixType &A_lcl, const ScalingFactorsViewType &scalingFactors, const bool assumeSymmetric)
Implementation details of Tpetra.
void leftScaleLocalCrsMatrix(const LocalSparseMatrixType &A_lcl, const ScalingFactorsViewType &scalingFactors, const bool assumeSymmetric, const bool divide=true)
Left-scale a KokkosSparse::CrsMatrix.
Namespace Tpetra contains the class and methods constituting the Tpetra library.