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/*
* Copyright 2008-2009 NVIDIA Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <cusp/blas.h>
#include <cusp/elementwise.h>
#include <cusp/multiply.h>
#include <cusp/detail/format_utils.h>
namespace cusp
{
namespace precond
{
namespace aggregation
{
namespace detail
{
template <typename Matrix>
void setup_level_matrix(Matrix& dst, Matrix& src) {
dst.swap(src);
}
template <typename Matrix1, typename Matrix2>
void setup_level_matrix(Matrix1& dst, Matrix2& src) {
dst = src;
}
} // end namespace detail
template <typename IndexType, typename ValueType, typename MemorySpace, typename SmootherType, typename SolverType>
template <typename MatrixType>
smoothed_aggregation<IndexType,ValueType,MemorySpace,SmootherType,SolverType>
::smoothed_aggregation(const MatrixType& A)
: sa_options(default_sa_options)
{
typedef typename cusp::array1d_view< thrust::constant_iterator<ValueType> > ConstantView;
ConstantView B(thrust::constant_iterator<ValueType>(1),
thrust::constant_iterator<ValueType>(1) + A.num_rows);
sa_initialize(A, B);
}
template <typename IndexType, typename ValueType, typename MemorySpace, typename SmootherType, typename SolverType>
template <typename MatrixType, typename Options>
smoothed_aggregation<IndexType,ValueType,MemorySpace,SmootherType,SolverType>
::smoothed_aggregation(const MatrixType& A,
const Options& sa_options)
: sa_options(sa_options)
{
typedef typename cusp::array1d_view< thrust::constant_iterator<ValueType> > ConstantView;
ConstantView B(thrust::constant_iterator<ValueType>(1),
thrust::constant_iterator<ValueType>(1) + A.num_rows);
sa_initialize(A, B);
}
template <typename IndexType, typename ValueType, typename MemorySpace, typename SmootherType, typename SolverType>
template <typename MatrixType>
smoothed_aggregation<IndexType,ValueType,MemorySpace,SmootherType,SolverType>
::smoothed_aggregation(const MatrixType& A, const cusp::array1d<ValueType,MemorySpace>& B)
: sa_options(default_sa_options)
{
sa_initialize(A, B);
}
template <typename IndexType, typename ValueType, typename MemorySpace, typename SmootherType, typename SolverType>
template <typename MatrixType, typename Options>
smoothed_aggregation<IndexType,ValueType,MemorySpace,SmootherType,SolverType>
::smoothed_aggregation(const MatrixType& A, const cusp::array1d<ValueType,MemorySpace>& B,
const Options& sa_options)
: sa_options(sa_options)
{
sa_initialize(A, B);
}
template <typename IndexType, typename ValueType, typename MemorySpace, typename SmootherType, typename SolverType>
template <typename MemorySpace2, typename SmootherType2, typename SolverType2>
smoothed_aggregation<IndexType,ValueType,MemorySpace,SmootherType,SolverType>
::smoothed_aggregation(const smoothed_aggregation<IndexType,ValueType,MemorySpace2,SmootherType2,SolverType2>& M)
: sa_options(M.sa_options), Parent(M)
{
for( size_t lvl = 0; lvl < M.sa_levels.size(); lvl++ )
sa_levels.push_back(M.sa_levels[lvl]);
}
template <typename IndexType, typename ValueType, typename MemorySpace, typename SmootherType, typename SolverType>
template <typename MatrixType, typename ArrayType>
void smoothed_aggregation<IndexType,ValueType,MemorySpace,SmootherType,SolverType>
::sa_initialize(const MatrixType& A, const ArrayType& B)
{
CUSP_PROFILE_SCOPED();
Parent* ML = this;
ML->levels.reserve(sa_options.max_levels); // avoid reallocations which force matrix copies
sa_levels.push_back(sa_level<SetupMatrixType>());
ML->levels.push_back(typename Parent::level());
sa_levels.back().B = B;
sa_levels.back().A_ = A; // copy
while ((sa_levels.back().A_.num_rows > sa_options.min_level_size) &&
(sa_levels.size() < sa_options.max_levels))
extend_hierarchy();
ML->solver = SolverType(sa_levels.back().A_);
// Setup solve matrix for each level
for( size_t lvl = 0; lvl < sa_levels.size(); lvl++ )
detail::setup_level_matrix( ML->levels[lvl].A, sa_levels[lvl].A_ );
}
template <typename IndexType, typename ValueType, typename MemorySpace, typename SmootherType, typename SolverType>
void smoothed_aggregation<IndexType,ValueType,MemorySpace,SmootherType,SolverType>
::extend_hierarchy(void)
{
CUSP_PROFILE_SCOPED();
Parent* ML = this;
cusp::array1d<IndexType,MemorySpace> aggregates;
{
// compute stength of connection matrix
SetupMatrixType C;
sa_options.strength_of_connection(sa_levels.back().A_, C);
// compute aggregates
aggregates.resize(C.num_rows);
cusp::blas::fill(aggregates,IndexType(0));
sa_options.aggregate(C, aggregates);
}
SetupMatrixType P;
cusp::array1d<ValueType,MemorySpace> B_coarse;
{
// compute tenative prolongator and coarse nullspace vector
SetupMatrixType T;
sa_options.fit_candidates(aggregates, sa_levels.back().B, T, B_coarse);
// compute prolongation operator
sa_options.smooth_prolongator(sa_levels.back().A_, T, P, sa_levels.back().rho_DinvA); // TODO if C != A then compute rho_Dinv_C
}
// compute restriction operator (transpose of prolongator)
SetupMatrixType R;
sa_options.form_restriction(P,R);
// construct Galerkin product R*A*P
SetupMatrixType RAP;
sa_options.galerkin_product(R,sa_levels.back().A_,P,RAP);
ML->levels.back().smoother = SmootherType(sa_levels.back());
sa_levels.back().aggregates.swap(aggregates);
detail::setup_level_matrix( ML->levels.back().R, R );
detail::setup_level_matrix( ML->levels.back().P, P );
ML->levels.back().residual.resize(sa_levels.back().A_.num_rows);
ML->levels.push_back(typename Parent::level());
sa_levels.push_back(sa_level<SetupMatrixType>());
sa_levels.back().A_.swap(RAP);
sa_levels.back().B.swap(B_coarse);
ML->levels.back().x.resize(sa_levels.back().A_.num_rows);
ML->levels.back().b.resize(sa_levels.back().A_.num_rows);
}
} // end namespace aggregation
} // end namespace precond
} // end namespace cusp
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