Description

An iterative solver based on modified Krylov iteration of MINRES type with gradient projections (similar to nonlinear CG with Polyak-Ribiere).

The PMINRES solver can use diagonal precondityioning (enabled by default).

See ChSystemDescriptor for more information about the problem formulation and the data structures passed to the solver.

Deprecated:: Use ChSolverMINRES instead. This class will be removed in a future Chrono release.

#include <ChSolverPMINRES.h>

Inheritance diagram for chrono::ChSolverPMINRES:

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Collaboration diagram for chrono::ChSolverPMINRES:

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Public Member Functions
virtual Type	GetType () const override
	Return type of the solver.

virtual double	Solve (ChSystemDescriptor &sysd) override
	Performs the solution of the problem. More...

double	Solve_SupportingStiffness (ChSystemDescriptor &sysd)
	Same as Solve(), but this also supports the presence of ChKRMBlock blocks. More...

void	SetGradDiffStep (double mf)
	For the case where inequalities are introduced, the gradient is projected. More...

double	GetGradDiffStep ()

void	SetRelTolerance (double mrt)
	Set relative tolerance. More...

double	GetRelTolerance ()

virtual double	GetError () const override
	Return the tolerance error reached during the last solve. More...

virtual void	ArchiveOut (ChArchiveOut &archive_out) override
	Method to allow serialization of transient data to archives.

virtual void	ArchiveIn (ChArchiveIn &archive_in) override
	Method to allow de-serialization of transient data from archives.

Public Member Functions inherited from chrono::ChIterativeSolverVI
void	SetOmega (double mval)
	Set the overrelaxation factor (default: 1.0). More...

void	SetSharpnessLambda (double mval)
	Set the sharpness factor (default: 1.0). More...

virtual void	SetMaxIterations (int max_iterations) override
	Set the maximum number of iterations.

void	SetRecordViolation (bool mval)
	Enable/disable recording of the constraint violation history. More...

double	GetOmega () const
	Return the current value of the overrelaxation factor.

double	GetSharpnessLambda () const
	Return the current value of the sharpness factor.

virtual int	GetIterations () const override
	Return the number of iterations performed during the last solve.

const std::vector< double > &	GetViolationHistory () const
	Access the vector of constraint violation history. More...

const std::vector< double > &	GetDeltalambdaHistory () const
	Access the vector with history of maximum change in Lagrange multipliers Note that collection of constraint violations must be enabled through SetRecordViolation.

Public Member Functions inherited from chrono::ChIterativeSolver
void	SetTolerance (double tolerance)
	Set the tolerance threshold used by the stopping criteria.

void	EnableDiagonalPreconditioner (bool val)
	Enable/disable use of a simple diagonal preconditioner (default: true). More...

void	EnableWarmStart (bool val)
	Enable/disable warm starting by providing an initial guess (default: false). More...

int	GetMaxIterations () const
	Get the current maximum number of iterations.

double	GetTolerance () const
	Get the current tolerance value.

Public Member Functions inherited from chrono::ChSolver
virtual ChDirectSolverLS *	AsDirect ()
	Downcast to ChDirectSolver.

virtual bool	Setup (ChSystemDescriptor &sysd)
	This function does the setup operations for the solver. More...

void	SetVerbose (bool mv)
	Set verbose output from solver.

void	EnableWrite (bool val, const std::string &frame, const std::string &out_dir=".")
	Enable/disable debug output of matrix, RHS, and solution vector.

Additional Inherited Members
Public Types inherited from chrono::ChSolver
enum	Type { Type::PSOR, Type::PSSOR, Type::PJACOBI, Type::PMINRES, Type::BARZILAIBORWEIN, Type::APGD, Type::ADMM, Type::SPARSE_LU, Type::SPARSE_QR, Type::PARDISO_MKL, Type::MUMPS, Type::GMRES, Type::MINRES, Type::BICGSTAB, CUSTOM }
	Available types of solvers. More...

Static Public Member Functions inherited from chrono::ChSolver
static std::string	GetTypeAsString (Type type)
	Return the solver type as a string.

Protected Member Functions inherited from chrono::ChIterativeSolverVI
virtual bool	IsIterative () const override
	Return true if iterative solver.

virtual bool	IsDirect () const override
	Return true if direct solver.

virtual ChIterativeSolver *	AsIterative () override
	Downcast to ChIterativeSolver.

void	AtIterationEnd (double mmaxviolation, double mdeltalambda, unsigned int iternum)
	This method MUST be called by all iterative methods INSIDE their iteration loops (at the end). More...

virtual bool	SolveRequiresMatrix () const override
	Indicate whether ot not the Solve() phase requires an up-to-date problem matrix. More...

Protected Member Functions inherited from chrono::ChIterativeSolver
	ChIterativeSolver (int max_iterations, double tolerance, bool use_precond, bool warm_start)

void	WriteMatrices (ChSystemDescriptor &sysd, bool one_indexed=true)

double	CheckSolution (ChSystemDescriptor &sysd, const ChVectorDynamic<> &x)

Protected Attributes inherited from chrono::ChIterativeSolverVI
int	m_iterations
	number of iterations performed by the solver during last call to Solve()

double	m_omega
	over-relaxation factor

double	m_shlambda
	sharpness factor

bool	record_violation_history

std::vector< double >	violation_history

std::vector< double >	dlambda_history

Protected Attributes inherited from chrono::ChIterativeSolver
bool	m_use_precond
	use diagonal preconditioning?

bool	m_warm_start
	use initial guesss?

int	m_max_iterations
	maximum number of iterations

double	m_tolerance
	tolerance threshold in stopping criteria

Protected Attributes inherited from chrono::ChSolver
bool	verbose

bool	write_matrix

std::string	output_dir

std::string	frame_id

Member Function Documentation

◆ GetError()

virtual double chrono::ChSolverPMINRES::GetError ( ) const

inlineoverridevirtual

Return the tolerance error reached during the last solve.

For the PMINRES solver, this is the norm of the projected residual.

Implements chrono::ChIterativeSolver.

◆ SetGradDiffStep()

void chrono::ChSolverPMINRES::SetGradDiffStep ( double mf )

inline

For the case where inequalities are introduced, the gradient is projected.

A numerical differentiation is used, this is the delta.

◆ SetRelTolerance()

void chrono::ChSolverPMINRES::SetRelTolerance ( double mrt )

inline

Set relative tolerance.

the iteration stops when the (projected) residual r is smaller than absolute tolerance, that you set via SetTolerance(), OR it is smaller than 'rhs_rel_tol' i.e. the norm of the right hand side multiplied by this relative tolerance. Set to 0 if you do not want relative tolerance to enter into play.

◆ Solve()

double chrono::ChSolverPMINRES::Solve ( ChSystemDescriptor & sysd )

overridevirtual

Performs the solution of the problem.

Returns: the maximum constraint violation after termination.

Parameters

sysd	system description with constraints and variables

Implements chrono::ChSolver.

◆ Solve_SupportingStiffness()

double chrono::ChSolverPMINRES::Solve_SupportingStiffness ( ChSystemDescriptor & sysd )

Same as Solve(), but this also supports the presence of ChKRMBlock blocks.

If Solve() is called and stiffness is present, Solve() automatically falls back to this function. It does not solve the Schur complement N*l-r=0 as Solve does, here the entire system KKT matrix with duals l and primals q is used.

double numerator = mr.MatrDot(mz,mZMr); // 1) r'* Z r double denominator = mr.MatrDot(mz_old,mZMr_old); // 2) r_old' Z *r_old