SLEPcEigenSolver Class Reference

This class provides an eigenvalue solver for PETSc matrices. It is a wrapper for the SLEPc eigenvalue solver. More...

#include <slepc.h>

Public Member Functions
	SLEPcEigenSolver (MPI_Comm comm)
	Create eigenvalue solver.
	SLEPcEigenSolver (EPS eps, bool inc_ref_count)
	Create eigenvalue solver from an existing EPS object.
	SLEPcEigenSolver (const SLEPcEigenSolver &)=delete
	SLEPcEigenSolver (SLEPcEigenSolver &&solver) noexcept
	Move constructor.
	~SLEPcEigenSolver ()
	Destructor.
SLEPcEigenSolver &	operator= (const SLEPcEigenSolver &)=delete
SLEPcEigenSolver &	operator= (SLEPcEigenSolver &&solver) noexcept
	Move assignment.
void	set_operators (const Mat A, const Mat B)
	Set the operators defining the eigenvalue problem.
EPSConvergedReason	solve ()
	Solve the eigenvalue problem \(A x = \lambda x\) (or \(A x = \lambda B x\)).
std::complex< PetscReal >	get_eigenvalue (PetscInt i) const
	Get the ith eigenvalue.
void	get_eigenpair (PetscScalar &lr, PetscScalar &lc, Vec r, Vec c, PetscInt i) const
	Get the ith eigenpair.
void	set_options_prefix (std::string_view options_prefix)
std::string	get_options_prefix () const
void	set_from_options () const
	Set options from the PETSc options database.
EPS	eps () const
	Return SLEPc EPS pointer.
MPI_Comm	comm () const
	Return MPI communicator.

Detailed Description

This class provides an eigenvalue solver for PETSc matrices. It is a wrapper for the SLEPc eigenvalue solver.

Constructor & Destructor Documentation

SLEPcEigenSolver() [1/2]

SLEPcEigenSolver ( MPI_Comm comm )

explicit

Create eigenvalue solver.

Note

SLEPc must have been initialised (SlepcInitialize) before this is called.

Parameters

[in]

comm

MPI communicator.

SLEPcEigenSolver() [2/2]

SLEPcEigenSolver	(	EPS	eps,
		bool	inc_ref_count )

Create eigenvalue solver from an existing EPS object.

Parameters

[in]	eps	SLEPc EPS object, which must already have been created. The reference count of eps is always decreased when this SLEPcEigenSolver is destroyed.
[in]	inc_ref_count	True if the reference count of eps should be incremented.

Member Function Documentation

get_eigenpair()

void get_eigenpair	(	PetscScalar &	lr,
		PetscScalar &	lc,
		Vec	r,
		Vec	c,
		PetscInt	i ) const

Get the ith eigenpair.

Parameters

[out]	lr	Real part of the eigenvalue.
[out]	lc	Imaginary part of the eigenvalue.
[out]	r	Real part of the eigenvector.
[out]	c	Imaginary part of the eigenvector.
[in]	i	Index of the eigenpair, in [0, nconv), where nconv is the number of converged eigenpairs reported by EPSGetConverged(eps(), &nconv).

Note

For a complex PETSc scalar type the eigenvalue and eigenvector are held entirely in lr and r, and lc and c are set to zero.

get_eigenvalue()

std::complex< PetscReal > get_eigenvalue

(

PetscInt

i

)

const

Get the ith eigenvalue.

Parameters

[in]

i

Index of the eigenvalue, in [0, nconv), where nconv is the number of converged eigenpairs reported by EPSGetConverged(eps(), &nconv).

Returns

The eigenvalue.

get_options_prefix()

std::string get_options_prefix

(

)

const

Returns the prefix used by PETSc when searching the PETSc options database

set_from_options()

void set_from_options

(

)

const

Set options from the PETSc options database.

Note

Call after set_options_prefix and after any settings the database should override.

set_operators()

void set_operators	(	const Mat	A,
		const Mat	B )

Set the operators defining the eigenvalue problem.

Parameters

[in]	A	Operator for the standard problem \(A x = \lambda x\), or the left-hand operator of the generalised problem \(A x = \lambda B x\). Must not be null.
[in]	B	Right-hand operator of the generalised problem, or nullptr for a standard eigenvalue problem.

set_options_prefix()

void set_options_prefix

(

std::string_view

options_prefix

)

Sets the prefix used by PETSc when searching the PETSc options database

solve()

EPSConvergedReason solve ( )

nodiscard

Solve the eigenvalue problem \(A x = \lambda x\) (or \(A x = \lambda B x\)).

Non-convergence is not treated as an error (a warning is logged); check the returned convergence reason.

Note

The number of eigenpairs to compute, and every other solver setting, is applied to the EPS object returned by eps(). SLEPc sizes its working subspace from the requested number, which defaults to one, e.g.

SLEPcEigenSolver solver(comm);
solver.set_operators(A, nullptr);
EPSSetDimensions(solver.eps(), 5, PETSC_DETERMINE, PETSC_DETERMINE);
EPSSetWhichEigenpairs(solver.eps(), EPS_SMALLEST_REAL);
solver.solve();

Returns

The PETSc convergence reason (positive on convergence, negative on divergence).

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

• /__w/dolfinx/dolfinx/cpp/dolfinx/la/slepc.h
• /__w/dolfinx/dolfinx/cpp/dolfinx/la/slepc.cpp