PETScWrappers::SolverBase Class Reference

#include <deal.II/lac/petsc_solver.h>

Inheritance diagram for PETScWrappers::SolverBase:

Public Member Functions
	SolverBase ()
	SolverBase (SolverControl &cn)
virtual	~SolverBase ()
void	solve (const MatrixBase &A, VectorBase &x, const VectorBase &b, const PreconditionBase &preconditioner)
virtual void	reset ()
void	set_prefix (const std::string &prefix)
SolverControl &	control () const
void	initialize (const PreconditionBase &preconditioner)
KSP	petsc_ksp ()
	operator KSP () const

Protected Member Functions
void	initialize_ksp_with_comm (const MPI_Comm comm)
virtual void	set_solver_type (KSP &ksp) const
void	perhaps_set_convergence_test () const

Protected Attributes
KSP	ksp
ObserverPointer< SolverControl, SolverBase >	solver_control
std::string	prefix_name

Static Private Member Functions
static PetscErrorCode	convergence_test (KSP ksp, const PetscInt iteration, const PetscReal residual_norm, KSPConvergedReason *reason, void *solver_control)

Friends
class	SLEPcWrappers::TransformationBase

Detailed Description

Base class for solver classes using the PETSc solvers. Since solvers in PETSc are selected based on flags passed to a generic solver object, basically all the actual solver calls happen in this class, and derived classes simply set the right flags to select one solver or another, or to set certain parameters for individual solvers.

Optionally, the user can create a solver derived from the SolverBase class and can set the default arguments necessary to solve the linear system of equations with SolverControl. These default options can be overridden by specifying command line arguments of the form -ksp_*. For example, -ksp_monitor_true_residual prints out true residual norm (unpreconditioned) at each iteration and -ksp_view provides information about the linear solver and the preconditioner used in the current context. The type of the solver can also be changed during runtime by specifying -ksp_type {richardson, cg, gmres, fgmres, ..} to dynamically test the optimal solver along with a suitable preconditioner set using -pc_type {jacobi, bjacobi, ilu, lu, ..}. There are several other command line options available to modify the behavior of the PETSc linear solver and can be obtained from the documentation and manual pages.

Note

Command line options relative to convergence tolerances are ignored when the solver is instantiated with a SolverControl.

Repeated calls to solve() on a solver object with a Preconditioner must be used with care. The preconditioner is initialized in the first call to solve() and subsequent calls reuse the solver and preconditioner object. This is done for performance reasons. The solver and preconditioner can be reset by calling reset() or by using the command line option "-ksp_reuse_preconditioner false".

Definition at line 91 of file petsc_solver.h.

Constructor & Destructor Documentation

SolverBase() [1/2]

SolverBase< VectorType >::SolverBase

(

)

Default constructor without SolverControl. The resulting solver will use PETSc's default convergence testing routines.

Definition at line 41 of file petsc_solver.cc.

SolverBase() [2/2]

SolverBase< VectorType >::SolverBase

(

SolverControl &

cn

)

Constructor with a SolverControl instance.

Definition at line 47 of file petsc_solver.cc.

~SolverBase()

SolverBase< VectorType >::~SolverBase ( )

virtual

Destructor.

Definition at line 60 of file petsc_solver.cc.

Member Function Documentation

solve()

void SolverBase< VectorType >::solve	(	const MatrixBase &	A,
		VectorBase &	x,
		const VectorBase &	b,
		const PreconditionBase &	preconditioner
	)

Solve the linear system Ax=b. Depending on the information provided by derived classes and the object passed as a preconditioner, one of the linear solvers and preconditioners of PETSc is chosen. Repeated calls to solve() do not reconstruct the preconditioner for performance reasons. See class Documentation.

Definition at line 83 of file petsc_solver.cc.

reset()

void SolverBase< VectorType >::reset ( )

virtual

Resets the contained preconditioner and solver object. See class description for more details.

Definition at line 148 of file petsc_solver.cc.

set_prefix()

void SolverBase< VectorType >::set_prefix

(

const std::string &

prefix

)

Sets a prefix name for the solver object. Useful when customizing the PETSc KSP object with command-line options.

Definition at line 141 of file petsc_solver.cc.

control()

SolverControl & SolverBase< VectorType >::control

(

)

const

Access to object that controls convergence.

Definition at line 155 of file petsc_solver.cc.

initialize()

void SolverBase< VectorType >::initialize

(

const PreconditionBase &

preconditioner

)

initialize the solver with the preconditioner. This function is intended for use with SLEPc spectral transformation class.

Definition at line 231 of file petsc_solver.cc.

petsc_ksp()

KSP SolverBase< VectorType >::petsc_ksp

(

)

Return the PETSc KSP object.

Definition at line 68 of file petsc_solver.cc.

operator KSP()

SolverBase< VectorType >::operator KSP

(

)

const

Conversion operator to gain access to the underlying PETSc type. If you do this, you cut this class off some information it may need, so this conversion operator should only be used if you know what you do.

Definition at line 75 of file petsc_solver.cc.

initialize_ksp_with_comm()

void SolverBase< VectorType >::initialize_ksp_with_comm ( const MPI_Comm  comm )

protected

Utility to create the KSP object and attach convergence test.

Definition at line 206 of file petsc_solver.cc.

set_solver_type()

void SolverBase< VectorType >::set_solver_type ( KSP &  ksp ) const

protectedvirtual

Function that takes a Krylov Subspace Solver context object, and sets the type of solver that is requested by the derived class.

Reimplemented in PETScWrappers::SolverRichardson, PETScWrappers::SolverChebychev, PETScWrappers::SolverCG, PETScWrappers::SolverBiCG, PETScWrappers::SolverGMRES, PETScWrappers::SolverBicgstab, PETScWrappers::SolverCGS, PETScWrappers::SolverTFQMR, PETScWrappers::SolverTCQMR, PETScWrappers::SolverCR, PETScWrappers::SolverLSQR, PETScWrappers::SolverPreOnly, and PETScWrappers::SparseDirectMUMPS.

Definition at line 55 of file petsc_solver.cc.

perhaps_set_convergence_test()

void SolverBase< VectorType >::perhaps_set_convergence_test ( ) const

protected

Utility to use deal.II convergence testing.

This call changes the convergence criterion when the instance of the class has a SolverControl object associated.

Definition at line 222 of file petsc_solver.cc.

convergence_test()

PetscErrorCode SolverBase< VectorType >::convergence_test ( KSP  ksp, const PetscInt  iteration, const PetscReal  residual_norm, KSPConvergedReason *  reason, void *  solver_control  )

staticprivate

A function that is used in PETSc as a callback to check on convergence. It takes the information provided from PETSc and checks it against deal.II's own SolverControl objects to see if convergence has been reached.

Definition at line 166 of file petsc_solver.cc.

Friends And Related Symbol Documentation

SLEPcWrappers::TransformationBase

friend class SLEPcWrappers::TransformationBase

friend

Definition at line 225 of file petsc_solver.h.

Member Data Documentation

ksp

KSP PETScWrappers::SolverBase::ksp

protected

The PETSc KSP object.

Definition at line 167 of file petsc_solver.h.

solver_control

ObserverPointer<SolverControl, SolverBase> PETScWrappers::SolverBase::solver_control

protected

Reference to the object that controls convergence of the iterative solver. In fact, for these PETSc wrappers, PETSc does so itself, but we copy the data from this object before starting the solution process, and copy the data back into it afterwards.

Definition at line 175 of file petsc_solver.h.

prefix_name

std::string PETScWrappers::SolverBase::prefix_name

protected

Solver prefix name to qualify options specific to the PETSc KSP object in the current context. Note: A hyphen (-) must NOT be given at the beginning of the prefix name. The first character of all runtime options is AUTOMATICALLY the hyphen.

Definition at line 205 of file petsc_solver.h.

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

• include/deal.II/lac/petsc_solver.h
• source/lac/petsc_solver.cc