A tag for algebraic multigrid (AMG). Used to transport information from the user to the implementation. More...

#include <amg_base.hpp>

Public Member Functions
	amg_tag ()
	The constructor, setting default values for the various parameters. More...

void	set_coarsening_method (amg_coarsening_method s)
	Sets the strategy used for constructing coarse grids. More...

amg_coarsening_method	get_coarsening_method () const
	Returns the current coarsening strategy. More...

void	set_interpolation_method (amg_interpolation_method interpol)
	Sets the interpolation method to the provided method. More...

amg_interpolation_method	get_interpolation_method () const
	Returns the current interpolation method. More...

void	set_strong_connection_threshold (double threshold)
	Sets the strong connection threshold. Customizations by the user essential for best results! More...

double	get_strong_connection_threshold () const
	Returns the strong connection threshold parameter. More...

void	set_jacobi_weight (double w)
	Sets the weight (damping) for the Jacobi smoother. More...

double	get_jacobi_weight () const
	Returns the Jacobi smoother weight (damping). More...

void	set_presmooth_steps (vcl_size_t steps)
	Sets the number of smoother applications on the fine level before restriction to the coarser level. More...

vcl_size_t	get_presmooth_steps () const
	Returns the number of smoother applications on the fine level before restriction to the coarser level. More...

void	set_postsmooth_steps (vcl_size_t steps)
	Sets the number of smoother applications on the coarse level before interpolation to the finer level. More...

vcl_size_t	get_postsmooth_steps () const
	Returns the number of smoother applications on the coarse level before interpolation to the finer level. More...

void	set_coarse_levels (vcl_size_t levels)
	Sets the number of coarse levels. If set to zero, then coarse levels are constructed until the cutoff size is reached. More...

vcl_size_t	get_coarse_levels () const
	Returns the number of coarse levels. If zero, then coarse levels are constructed until the cutoff size is reached. More...

void	set_coarsening_cutoff (vcl_size_t size)
	Sets the coarse grid size for which the recursive multigrid scheme is stopped and a direct solver is used. More...

vcl_size_t	get_coarsening_cutoff () const
	Returns the coarse grid size for which the recursive multigrid scheme is stopped and a direct solver is used. More...

void	set_setup_context (viennacl::context ctx)
	Sets the ViennaCL context for the setup stage. Set this to a host context if you want to run the setup on the host. More...

viennacl::context const &	get_setup_context () const
	Returns the ViennaCL context for the preconditioenr setup. More...

void	set_target_context (viennacl::context ctx)
	Sets the ViennaCL context for the solver cycle stage (i.e. preconditioner applications). More...

viennacl::context const &	get_target_context () const
	Returns the ViennaCL context for the solver cycle stage (i.e. preconditioner applications). More...

Detailed Description

A tag for algebraic multigrid (AMG). Used to transport information from the user to the implementation.

Examples:: amg.cpp.

Definition at line 64 of file amg_base.hpp.

Constructor & Destructor Documentation

viennacl::linalg::amg_tag::amg_tag ( )

inline

The constructor, setting default values for the various parameters.

Default coarsening routine: Aggreggation based on maximum independent sets of distance (MIS-2) Default interpolation routine: Smoothed aggregation Default threshold for strong connections: 0.1 (customizations are recommeded!) Default weight for Jacobi smoother: 1.0 Default number of pre-smooth operations: 2 Default number of post-smooth operations: 2 Default number of coarse levels: 0 (this indicates that as many coarse levels as needed are constructed until the cutoff is reached) Default coarse grid size for direct solver (coarsening cutoff): 50

Definition at line 78 of file amg_base.hpp.

Member Function Documentation

vcl_size_t viennacl::linalg::amg_tag::get_coarse_levels ( ) const

inline

Returns the number of coarse levels. If zero, then coarse levels are constructed until the cutoff size is reached.

Definition at line 128 of file amg_base.hpp.

vcl_size_t viennacl::linalg::amg_tag::get_coarsening_cutoff ( ) const

inline

Returns the coarse grid size for which the recursive multigrid scheme is stopped and a direct solver is used.

Definition at line 133 of file amg_base.hpp.

amg_coarsening_method viennacl::linalg::amg_tag::get_coarsening_method ( ) const

inline

Returns the current coarsening strategy.

Definition at line 88 of file amg_base.hpp.

amg_interpolation_method viennacl::linalg::amg_tag::get_interpolation_method ( ) const

inline

Returns the current interpolation method.

Definition at line 93 of file amg_base.hpp.

double viennacl::linalg::amg_tag::get_jacobi_weight ( ) const

inline

Returns the Jacobi smoother weight (damping).

Definition at line 113 of file amg_base.hpp.

vcl_size_t viennacl::linalg::amg_tag::get_postsmooth_steps ( ) const

inline

Returns the number of smoother applications on the coarse level before interpolation to the finer level.

Definition at line 123 of file amg_base.hpp.

vcl_size_t viennacl::linalg::amg_tag::get_presmooth_steps ( ) const

inline

Returns the number of smoother applications on the fine level before restriction to the coarser level.

Definition at line 118 of file amg_base.hpp.

viennacl::context const& viennacl::linalg::amg_tag::get_setup_context ( ) const

inline

Returns the ViennaCL context for the preconditioenr setup.

Definition at line 142 of file amg_base.hpp.

double viennacl::linalg::amg_tag::get_strong_connection_threshold ( ) const

inline

Returns the strong connection threshold parameter.

See also: set_strong_connection_threshold() for an explanation of the threshold parameter

Definition at line 105 of file amg_base.hpp.

viennacl::context const& viennacl::linalg::amg_tag::get_target_context ( ) const

inline

Returns the ViennaCL context for the solver cycle stage (i.e. preconditioner applications).

Definition at line 150 of file amg_base.hpp.

void viennacl::linalg::amg_tag::set_coarse_levels ( vcl_size_t levels )

inline

Sets the number of coarse levels. If set to zero, then coarse levels are constructed until the cutoff size is reached.

Definition at line 126 of file amg_base.hpp.

void viennacl::linalg::amg_tag::set_coarsening_cutoff ( vcl_size_t size )

inline

Sets the coarse grid size for which the recursive multigrid scheme is stopped and a direct solver is used.

Definition at line 131 of file amg_base.hpp.

void viennacl::linalg::amg_tag::set_coarsening_method ( amg_coarsening_method s )

inline

Sets the strategy used for constructing coarse grids.

Examples:: amg.cpp.

Definition at line 86 of file amg_base.hpp.

void viennacl::linalg::amg_tag::set_interpolation_method ( amg_interpolation_method interpol )

inline

Sets the interpolation method to the provided method.

Examples:: amg.cpp.

Definition at line 91 of file amg_base.hpp.

void viennacl::linalg::amg_tag::set_jacobi_weight ( double w )

inline

Sets the weight (damping) for the Jacobi smoother.

The optimal value depends on the problem at hand. Values of 0.67 or 1.0 are usually a good starting point for further experiments.

Examples:: amg.cpp.

Definition at line 111 of file amg_base.hpp.

void viennacl::linalg::amg_tag::set_postsmooth_steps ( vcl_size_t steps )

inline

Sets the number of smoother applications on the coarse level before interpolation to the finer level.

Examples:: amg.cpp.

Definition at line 121 of file amg_base.hpp.

void viennacl::linalg::amg_tag::set_presmooth_steps ( vcl_size_t steps )

inline

Sets the number of smoother applications on the fine level before restriction to the coarser level.

Examples:: amg.cpp.

Definition at line 116 of file amg_base.hpp.

void viennacl::linalg::amg_tag::set_setup_context ( viennacl::context ctx )

inline

Sets the ViennaCL context for the setup stage. Set this to a host context if you want to run the setup on the host.

Set the ViennaCL context for the solver application via set_target_context(). Target and setup context can be different.

Examples:: amg.cpp.

Definition at line 140 of file amg_base.hpp.

void viennacl::linalg::amg_tag::set_strong_connection_threshold ( double threshold )

inline

Sets the strong connection threshold. Customizations by the user essential for best results!

With classical interpolation, a connection is considered strong if |a_ij| >= threshold * max_k(|a_ik|) Strength of connection currently ignored for aggregation-based coarsening (to be added in the future).

Examples:: amg.cpp.

Definition at line 100 of file amg_base.hpp.

void viennacl::linalg::amg_tag::set_target_context ( viennacl::context ctx )

inline

Sets the ViennaCL context for the solver cycle stage (i.e. preconditioner applications).

Since the cycle stage easily benefits from accelerators, you usually want to set this to a CUDA or OpenCL-enabled context.

Examples:: amg.cpp.

Definition at line 148 of file amg_base.hpp.

The documentation for this class was generated from the following file:

viennacl/linalg/detail/amg/amg_base.hpp

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation