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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.
*/
/*! \file jacobi.inl
* \brief Inline file for jacobi.h
*/
#include <cusp/multiply.h>
#include <cusp/detail/format_utils.h>
#include <cusp/precond/aggregation/smoothed_aggregation_options.h>
#include <thrust/functional.h>
#include <thrust/transform.h>
#include <thrust/iterator/zip_iterator.h>
namespace cusp
{
namespace relaxation
{
namespace detail
{
template <typename ValueType>
struct jacobi_presmooth_functor
{
ValueType omega;
jacobi_presmooth_functor(ValueType omega) : omega(omega) {}
__host__ __device__
ValueType operator()(const ValueType& b, const ValueType& d) const
{
return omega * b / d;
}
};
template <typename ValueType>
struct jacobi_postsmooth_functor
{
ValueType omega;
jacobi_postsmooth_functor(ValueType omega) : omega(omega) {}
template <typename Tuple>
__host__ __device__
ValueType operator()(const Tuple& t)
{
const ValueType x = thrust::get<0>(t);
const ValueType d = thrust::get<1>(t);
const ValueType b = thrust::get<2>(t);
const ValueType y = thrust::get<3>(t);
return x + omega * (b - y) / d;
}
};
} // end namespace detail
// constructor
template <typename ValueType, typename MemorySpace>
jacobi<ValueType,MemorySpace>
::jacobi() : default_omega(0.0)
{
}
template <typename ValueType, typename MemorySpace>
template<typename MemorySpace2>
jacobi<ValueType,MemorySpace>
::jacobi(const jacobi<ValueType,MemorySpace2>& A)
: default_omega(A.default_omega), temp(A.temp), diagonal(A.diagonal)
{
}
template <typename ValueType, typename MemorySpace>
template<typename MatrixType>
jacobi<ValueType,MemorySpace>
::jacobi(const MatrixType& A, ValueType omega)
: default_omega(omega), temp(A.num_rows)
{
CUSP_PROFILE_SCOPED();
// extract the main diagonal
cusp::detail::extract_diagonal(A, diagonal);
}
template <typename ValueType, typename MemorySpace>
template<typename MatrixType>
jacobi<ValueType,MemorySpace>
::jacobi(const cusp::precond::aggregation::sa_level<MatrixType>& sa_level, ValueType weight)
: temp(sa_level.A_.num_rows)
{
CUSP_PROFILE_SCOPED();
if(sa_level.rho_DinvA == ValueType(0))
{
default_omega = weight / cusp::precond::aggregation::detail::estimate_rho_Dinv_A(sa_level.A_);
}
else
{
default_omega = weight / sa_level.rho_DinvA;
}
// extract the main diagonal
cusp::detail::extract_diagonal(sa_level.A_, diagonal);
}
// linear_operator
template <typename ValueType, typename MemorySpace>
template<typename MatrixType, typename VectorType1, typename VectorType2>
void jacobi<ValueType,MemorySpace>
::operator()(const MatrixType& A, const VectorType1& b, VectorType2& x)
{
jacobi<ValueType,MemorySpace>::operator()(A,b,x,default_omega);
}
// override default omega
template <typename ValueType, typename MemorySpace>
template<typename MatrixType, typename VectorType1, typename VectorType2>
void jacobi<ValueType,MemorySpace>
::operator()(const MatrixType& A, const VectorType1& b, VectorType2& x, ValueType omega)
{
CUSP_PROFILE_SCOPED();
// y <- A*x
cusp::multiply(A, x, temp);
// x <- x + omega * D^-1 * (b - y)
thrust::transform(thrust::make_zip_iterator(thrust::make_tuple(x.begin(), diagonal.begin(), b.begin(), temp.begin())),
thrust::make_zip_iterator(thrust::make_tuple(x.end(), diagonal.end(), b.end(), temp.end())),
x.begin(),
detail::jacobi_postsmooth_functor<ValueType>(omega));
}
template <typename ValueType, typename MemorySpace>
template<typename MatrixType, typename VectorType1, typename VectorType2>
void jacobi<ValueType,MemorySpace>
::presmooth(const MatrixType&, const VectorType1& b, VectorType2& x)
{
CUSP_PROFILE_SCOPED();
// x <- omega * D^-1 * b
thrust::transform(b.begin(), b.end(),
diagonal.begin(),
x.begin(),
detail::jacobi_presmooth_functor<ValueType>(default_omega));
}
template <typename ValueType, typename MemorySpace>
template<typename MatrixType, typename VectorType1, typename VectorType2>
void jacobi<ValueType,MemorySpace>
::postsmooth(const MatrixType& A, const VectorType1& b, VectorType2& x)
{
CUSP_PROFILE_SCOPED();
// y <- A*x
cusp::multiply(A, x, temp);
// x <- x + omega * D^-1 * (b - y)
thrust::transform(thrust::make_zip_iterator(thrust::make_tuple(x.begin(), diagonal.begin(), b.begin(), temp.begin())),
thrust::make_zip_iterator(thrust::make_tuple(x.end(), diagonal.end(), b.end(), temp.end())),
x.begin(),
detail::jacobi_postsmooth_functor<ValueType>(default_omega));
}
} // end namespace relaxation
} // end namespace cusp
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