CG-family solvers (BiCGStab or CG) for use as the bottom solver in MLMG. More...

#include <AMReX_MLCGSolver.H>

Public Types
enum struct	Type { BiCGStab , CG }

using	FAB = typename MLLinOpT< MF >::FAB

using	RT = typename MLLinOpT< MF >::RT

Public Member Functions
	MLCGSolverT (MLLinOpT< MF > &_lp, Type _typ=Type::BiCGStab)
	Construct a solver bound to `_lp`.

	~MLCGSolverT ()

	MLCGSolverT (const MLCGSolverT< MF > &rhs)=delete

	MLCGSolverT (MLCGSolverT< MF > &&rhs)=delete

MLCGSolverT< MF > &	operator= (const MLCGSolverT< MF > &rhs)=delete

MLCGSolverT< MF > &	operator= (MLCGSolverT< MF > &&rhs)=delete

void	setSolver (Type _typ) noexcept
	Switch between BiCGStab and CG after construction.

int	solve (MF &solnL, const MF &rhsL, RT eps_rel, RT eps_abs)
	Solve Lp(solnL)=rhsL to the requested tolerance.

void	setVerbose (int _verbose)
	Control how much logging is emitted (0 = silent).

int	getVerbose () const
	Current verbosity level.

void	setMaxIter (int _maxiter)
	Cap the number of Krylov iterations performed.

int	getMaxIter () const
	Current iteration cap.

void	setPrintIdentation (std::string s)
	Prefix printed messages (e.g., to indent per level).

void	setInitSolnZeroed (bool _sol_zeroed)

bool	getInitSolnZeroed () const
	Whether setInitSolnZeroed(true) was requested.

void	setNGhost (int _nghost)
	Set the number of grow cells used when allocating temporaries.

int	getNGhost ()
	Current grow-cell count (same in every direction).

RT	dotxy (const MF &r, const MF &z, bool local=false)
	Dot product helper; set `local` to true to skip the MPI reduction.

RT	norm_inf (const MF &res, bool local=false)
	Infinity norm helper; set `local` to true to skip the MPI reduction.

int	solve_bicgstab (MF &solnL, const MF &rhsL, RT eps_rel, RT eps_abs)
	Raw BiCGStab implementation mirroring the high-level solve() signature.

int	solve_cg (MF &solnL, const MF &rhsL, RT eps_rel, RT eps_abs)
	Raw CG implementation mirroring the high-level solve() signature.

int	getNumIters () const noexcept
	Iteration count from the last solve* call (or -1 if unused).

Detailed Description

template<typename MF>
class amrex::MLCGSolverT< MF >

CG-family solvers (BiCGStab or CG) for use as the bottom solver in MLMG.

Member Typedef Documentation

◆ FAB

template<typename MF >

using amrex::MLCGSolverT< MF >::FAB = typename MLLinOpT<MF>::FAB

◆ RT

template<typename MF >

using amrex::MLCGSolverT< MF >::RT = typename MLLinOpT<MF>::RT

Member Enumeration Documentation

◆ Type

template<typename MF >

enum struct amrex::MLCGSolverT::Type

strong

Enumerator
BiCGStab
CG

Constructor & Destructor Documentation

◆ MLCGSolverT() [1/3]

template<typename MF >

amrex::MLCGSolverT< MF >::MLCGSolverT	(	MLLinOpT< MF > &	_lp,
		Type	_typ = `Type::BiCGStab`
	)

Construct a solver bound to _lp.

Parameters

_lp	Linear operator that supplies apply/normalization hooks.
_typ	Solver flavor (BiCGStab by default).

◆ ~MLCGSolverT()

template<typename MF >

amrex::MLCGSolverT< MF >::~MLCGSolverT ( )

default

◆ MLCGSolverT() [2/3]

template<typename MF >

amrex::MLCGSolverT< MF >::MLCGSolverT ( const MLCGSolverT< MF > & rhs )

delete

◆ MLCGSolverT() [3/3]

template<typename MF >

amrex::MLCGSolverT< MF >::MLCGSolverT ( MLCGSolverT< MF > && rhs )

delete

Member Function Documentation

◆ dotxy()

template<typename MF >

auto amrex::MLCGSolverT< MF >::dotxy	(	const MF &	r,
		const MF &	z,
		bool	local = `false`
	)

Dot product helper; set local to true to skip the MPI reduction.

Parameters

r	First vector.
z	Second vector.
local	True to limit the operation to local data only.

Returns: Dot product of r and z (globally reduced unless local is true).

◆ getInitSolnZeroed()

template<typename MF >

bool amrex::MLCGSolverT< MF >::getInitSolnZeroed ( ) const

inline

Whether setInitSolnZeroed(true) was requested.

◆ getMaxIter()

template<typename MF >

int amrex::MLCGSolverT< MF >::getMaxIter ( ) const

inline

Current iteration cap.

◆ getNGhost()

template<typename MF >

int amrex::MLCGSolverT< MF >::getNGhost ( )

inline

Current grow-cell count (same in every direction).

◆ getNumIters()

template<typename MF >

int amrex::MLCGSolverT< MF >::getNumIters ( ) const

inlinenoexcept

Iteration count from the last solve* call (or -1 if unused).

◆ getVerbose()

template<typename MF >

int amrex::MLCGSolverT< MF >::getVerbose ( ) const

inline

Current verbosity level.

◆ norm_inf()

template<typename MF >

auto amrex::MLCGSolverT< MF >::norm_inf	(	const MF &	res,
		bool	local = `false`
	)

Infinity norm helper; set local to true to skip the MPI reduction.

Parameters

res	Vector whose infinity norm is measured.
local	True to limit the operation to local data only.

Returns: Infinity norm of res (globally reduced unless local is true).

◆ operator=() [1/2]

template<typename MF >

MLCGSolverT< MF > & amrex::MLCGSolverT< MF >::operator= ( const MLCGSolverT< MF > & rhs )

delete

◆ operator=() [2/2]

template<typename MF >

MLCGSolverT< MF > & amrex::MLCGSolverT< MF >::operator= ( MLCGSolverT< MF > && rhs )

delete

◆ setInitSolnZeroed()

template<typename MF >

void amrex::MLCGSolverT< MF >::setInitSolnZeroed ( bool _sol_zeroed )

inline

Is the initial guess provided to the solver zero? If so, set this to true so the solver can skip extra work. Default is false.

Parameters

_sol_zeroed True if the initial guess is zero everywhere.

◆ setMaxIter()

template<typename MF >

void amrex::MLCGSolverT< MF >::setMaxIter ( int _maxiter )

inline

Cap the number of Krylov iterations performed.

Parameters

_maxiter Maximum number of BiCGStab/CG iterations.

◆ setNGhost()

template<typename MF >

void amrex::MLCGSolverT< MF >::setNGhost ( int _nghost )

inline

Set the number of grow cells used when allocating temporaries.

Parameters

_nghost Grow-cell count applied uniformly in each direction.

◆ setPrintIdentation()

template<typename MF >

void amrex::MLCGSolverT< MF >::setPrintIdentation ( std::string s )

inline

Prefix printed messages (e.g., to indent per level).

Parameters

s	String inserted at the beginning of each log line.

◆ setSolver()

template<typename MF >

void amrex::MLCGSolverT< MF >::setSolver ( Type _typ )

inlinenoexcept

Switch between BiCGStab and CG after construction.

Parameters

_typ	New solver flavor.

◆ setVerbose()

template<typename MF >

void amrex::MLCGSolverT< MF >::setVerbose ( int _verbose )

inline

Control how much logging is emitted (0 = silent).

Parameters

_verbose Verbosity level printed by the solver.

◆ solve()

template<typename MF >

int amrex::MLCGSolverT< MF >::solve	(	MF &	solnL,
		const MF &	rhsL,
		RT	eps_rel,
		RT	eps_abs
	)

Solve Lp(solnL)=rhsL to the requested tolerance.

Parameters

solnL	On input: initial guess; on output: solution.
rhsL	Right-hand side.
eps_rel	Relative tolerance on the residual.
eps_abs	Absolute tolerance on the residual.

Returns: 0 success; 1 breakdown (BiCGStab: rho = 0; CG: rho = 0 or p^T q = 0); 2 BiCGStab only: rh^T v = 0; 3 BiCGStab only: t^T t = 0 in the omega update; 4 BiCGStab only: omega = 0; 8 non-convergence (iteration limit reached); 9 non-convergence but residual improved vs. the initial guess.

◆ solve_bicgstab()

template<typename MF >

int amrex::MLCGSolverT< MF >::solve_bicgstab	(	MF &	solnL,
		const MF &	rhsL,
		RT	eps_rel,
		RT	eps_abs
	)

Raw BiCGStab implementation mirroring the high-level solve() signature.

Parameters

solnL	Solution vector (initial guess on input).
rhsL	Right-hand side.
eps_rel	Relative residual tolerance.
eps_abs	Absolute residual tolerance.

Returns: Same status codes as solve().

◆ solve_cg()

template<typename MF >

int amrex::MLCGSolverT< MF >::solve_cg	(	MF &	solnL,
		const MF &	rhsL,
		RT	eps_rel,
		RT	eps_abs
	)

Raw CG implementation mirroring the high-level solve() signature.

Parameters

solnL	Solution vector (initial guess on input).
rhsL	Right-hand side.
eps_rel	Relative residual tolerance.
eps_abs	Absolute residual tolerance.

Returns: Same status codes as solve().

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

/home/runner/work/amrex/amrex/Src/LinearSolvers/MLMG/AMReX_MLCGSolver.H

Public Types

Public Member Functions

Detailed Description

Member Typedef Documentation

◆ FAB

◆ RT

Member Enumeration Documentation

◆ Type

Constructor & Destructor Documentation

◆ MLCGSolverT() [1/3]

◆ ~MLCGSolverT()

◆ MLCGSolverT() [2/3]

◆ MLCGSolverT() [3/3]

Member Function Documentation

◆ dotxy()

◆ getInitSolnZeroed()

◆ getMaxIter()

◆ getNGhost()

◆ getNumIters()

◆ getVerbose()

◆ norm_inf()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ setInitSolnZeroed()

◆ setMaxIter()

◆ setNGhost()

◆ setPrintIdentation()

◆ setSolver()

◆ setVerbose()

◆ solve()

◆ solve_bicgstab()

◆ solve_cg()