Reimplementing the Jacobi solver. (c5b307bb) · Commits · TNL / tnl-dev

src/TNL/Solvers/Linear/Jacobi.h

+15 −2

Original line number	Diff line number	Diff line
		@@ -61,7 +61,8 @@ class Jacobi
		* In addition to config entries defined by \ref IterativeSolver::configSetup, this method
		* defines the following:
		*
		* \e jacobi-omega - relaxation parameter of the weighted/damped Jacobi method.
		* \e jacobi-omega - relaxation parameter of the weighted/damped Jacobi method - 1.0 by default.
		* \e residue-period - says after how many iterations the reside is recomputed - 4 by default.
		*
		* \param config contains description of configuration parameters.
		* \param prefix is a prefix of particular configuration entries.
		@@ -103,7 +104,19 @@ class Jacobi
		bool solve( ConstVectorViewType b, VectorViewType x ) override;

		protected:
		RealType omega = 0.0;

		using VectorType = TNL::Containers::Vector< RealType, DeviceType, IndexType >;

		void performIteration( const ConstVectorViewType& b,
		const ConstVectorViewType& diagonalView,
		const ConstVectorViewType& in,
		VectorViewType& out ) const;

		RealType omega = 1.0;

		IndexType residuePeriod = 4;

		VectorType diagonal;
		};

		} // namespace Linear

src/TNL/Solvers/Linear/Jacobi.hpp

+43 −9

Original line number	Diff line number	Diff line
		@@ -11,6 +11,7 @@
		#include <TNL/Containers/Vector.h>
		#include <TNL/Solvers/Linear/LinearSolver.h>
		#include <TNL/Solvers/Linear/Utils/LinearResidueGetter.h>
		#include <TNL/Functional.h>

		namespace TNL {
		namespace Solvers {
		@@ -23,12 +24,13 @@ configSetup( Config::ConfigDescription& config, const String& prefix )
		{
		LinearSolver< Matrix >::configSetup( config, prefix );
		config.addEntry< double >( prefix + "jacobi-omega", "Relaxation parameter of the weighted/damped Jacobi method.", 1.0 );
		config.addEntry< int >( prefix + "residue-period", "Says after how many iterations the reside is recomputed.", 4 );
		}

		template< typename Matrix >
		bool
		Jacobi< Matrix >::
		setup( const Config::ParameterContainer& parameters, const String& prefix ) override
		setup( const Config::ParameterContainer& parameters, const String& prefix )
		{
		if( parameters.checkParameter( prefix + "jacobi-omega" ) )
		this->setOmega( parameters.getParameter< double >( prefix + "jacobi-omega" ) );
		@@ -58,30 +60,62 @@ getOmega() const -> RealType
		template< typename Matrix >
		bool
		Jacobi< Matrix >::
		solve( ConstVectorViewType b, VectorViewType x ) override
		solve( ConstVectorViewType b, VectorViewType x )
		{
		const IndexType size = this->matrix->getRows();

		Containers::Vector< RealType, DeviceType, IndexType > aux;
		aux.setSize( size );

		/////
		// Fetch diagonal elements
		this->diagonal.setSize( size );
		auto diagonalView = this->diagonal.getView();
		auto fetch_diagonal = [=] __cuda_callable__ ( IndexType rowIdx, IndexType localIdx, const IndexType& columnIdx, const RealType& value ) mutable {
		if( columnIdx == rowIdx ) diagonalView[ rowIdx ] = value;
		};
		this->matrix->forAllElements( fetch_diagonal );

		this->resetIterations();
		this->setResidue( this->getConvergenceResidue() + 1.0 );

		RealType bNorm = b.lpNorm( ( RealType ) 2.0 );
		auto bView = b.getView();
		auto xView = x.getView();
		auto auxView = aux.getView();
		RealType bNorm = lpNorm( b, ( RealType ) 2.0 );
		aux = x;
		while( this->nextIteration() )
		{
		for( IndexType row = 0; row < size; row ++ )
		this->matrix->performJacobiIteration( b, row, x, aux, this->getOmega() );
		for( IndexType row = 0; row < size; row ++ )
		this->matrix->performJacobiIteration( b, row, aux, x, this->getOmega() );
		this->performIteration( bView, diagonalView, xView, auxView );
		if( this->getIterations() % this->residuePeriod == 0 )
		this->setResidue( LinearResidueGetter::getResidue( *this->matrix, x, b, bNorm ) );
		this->currentIteration++;
		this->performIteration( bView, diagonalView, auxView, xView );
		if( ( this->getIterations() ) % this->residuePeriod == 0 )
		this->setResidue( LinearResidueGetter::getResidue( *this->matrix, x, b, bNorm ) );

		}
		this->setResidue( LinearResidueGetter::getResidue( *this->matrix, x, b, bNorm ) );
		return this->checkConvergence();
		}

		template< typename Matrix >
		void
		Jacobi< Matrix >::
		performIteration( const ConstVectorViewType& b,
		const ConstVectorViewType& diagonalView,
		const ConstVectorViewType& in,
		VectorViewType& out ) const
		{
		const RealType omega_ = this->omega;
		auto fetch = [=] __cuda_callable__ ( IndexType rowIdx, IndexType columnIdx, const RealType& value ) {
		return value * in[ columnIdx ];
		};
		auto keep = [=] __cuda_callable__ ( IndexType rowIdx, const RealType& value ) mutable {
		out[ rowIdx ] = in[ rowIdx ] + omega_ / diagonalView[ rowIdx ] * ( b[ rowIdx ] - value );
		};
		this->matrix->reduceAllRows( fetch, TNL::Plus{}, keep, 0.0 );
		}

		} // namespace Linear
		} // namespace Solvers
		} // namespace TNL