Nektar::LibUtilities::NekNonlinSysNewton Class Reference

#include <NekNonlinSysNewton.h>

Inheritance diagram for Nektar::LibUtilities::NekNonlinSysNewton:

Public Member Functions
	NekNonlinSysNewton (const LibUtilities::SessionReaderSharedPtr &pSession, const LibUtilities::CommSharedPtr &vRowComm, const int nscale, const NekSysKey &pKey)
	~NekNonlinSysNewton () override=default
Public Member Functions inherited from Nektar::LibUtilities::NekNonlinSys
	NekNonlinSys (const LibUtilities::SessionReaderSharedPtr &pSession, const LibUtilities::CommSharedPtr &vRowComm, const int nDimen, const NekSysKey &pKey)
	~NekNonlinSys () override=default
const Array< OneD, const NekDouble > &	GetRefSolution () const
const Array< OneD, const NekDouble > &	GetRefResidual () const
const Array< OneD, const NekDouble > &	GetRefSourceVec () const
const NekLinSysIterSharedPtr &	GetLinSys ()
int	GetNtotLinSysIts ()
void	SetNekNonlinSysTolerance (const NekDouble in)
void	SetNekNonlinSysMaxIterations (const unsigned int in)
void	SetNonlinIterTolRelativeL2 (const NekDouble in)
void	SetLinSysRelativeTolInNonlin (const NekDouble in)
Public Member Functions inherited from Nektar::LibUtilities::NekSys
	NekSys (const LibUtilities::SessionReaderSharedPtr &pSession, const LibUtilities::CommSharedPtr &vRowComm, const int nDimen, const NekSysKey &pKey)
virtual	~NekSys ()=default
void	InitObject ()
void	SetSysOperators (const NekSysOperators &in)
const NekSysOperators &	GetSysOperators ()
int	SolveSystem (const int nGlobal, const Array< OneD, const NekDouble > &pInput, Array< OneD, NekDouble > &pOutput, const int nDir, const NekDouble tol=1.0E-7, const NekDouble factor=1.0)
bool	ConvergenceCheck (const int nIteration, const Array< OneD, const NekDouble > &Residual, const NekDouble tol=1.0E-7)
void	SetFlagWarnings (bool in)

Static Public Member Functions
static NekNonlinSysSharedPtr	create (const LibUtilities::SessionReaderSharedPtr &pSession, const LibUtilities::CommSharedPtr &vRowComm, const int nDimen, const NekSysKey &pKey)
Static Public Member Functions inherited from Nektar::LibUtilities::NekSys
static NekSysSharedPtr	CreateInstance (const LibUtilities::SessionReaderSharedPtr &pSession, const LibUtilities::CommSharedPtr &vRowComm, const int nDimen, const NekSysKey &pKey)

Static Public Attributes
static std::string	className

Protected Member Functions
void	v_InitObject () override
void	v_SetSysOperators (const NekSysOperators &in) override
int	v_SolveSystem (const int nGlobal, const Array< OneD, const NekDouble > &pInput, Array< OneD, NekDouble > &pOutput, const int nDir, const NekDouble tol, const NekDouble factor) override
bool	v_ConvergenceCheck (const int nIteration, const Array< OneD, const NekDouble > &Residual, const NekDouble tol) override
void	v_InitObject () override
Protected Member Functions inherited from Nektar::LibUtilities::NekSys
virtual void	v_InitObject ()
virtual void	v_SetSysOperators (const NekSysOperators &in)
virtual int	v_SolveSystem (const int nGlobal, const Array< OneD, const NekDouble > &pInput, Array< OneD, NekDouble > &pOutput, const int nDir, const NekDouble tol, const NekDouble factor)
virtual bool	v_ConvergenceCheck (const int nIteration, const Array< OneD, const NekDouble > &Residual, const NekDouble tol)
virtual void	v_NekSysInitialGuess (const Array< OneD, const NekDouble > &pInput, Array< OneD, NekDouble > &pguess)

Protected Attributes
NekDouble	m_SysResNorm0
NekDouble	m_SysResNorm
bool	m_InexactNewtonForcing = 0
NekDouble	m_forcingGamma = 1.0
NekDouble	m_forcingAlpha = 0.5 * (1.0 + sqrt(5.0))
Protected Attributes inherited from Nektar::LibUtilities::NekNonlinSys
NekLinSysIterSharedPtr	m_linsol
NekDouble	m_NonlinIterTolRelativeL2
NekDouble	m_LinSysRelativeTolInNonlin
std::string	m_LinSysIterSolverType
int	m_totalIterations = 0
int	m_NtotLinSysIts = 0
Array< OneD, NekDouble >	m_Solution
Array< OneD, NekDouble >	m_Residual
Array< OneD, NekDouble >	m_DeltSltn
Array< OneD, NekDouble >	m_SourceVec
Protected Attributes inherited from Nektar::LibUtilities::NekSys
int	m_maxiter
	Maximum iterations. More...
NekDouble	m_tolerance
	Tolerance of iterative solver. More...
LibUtilities::CommSharedPtr	m_rowComm
	Communicate. More...
bool	m_converged
	Whether the iteration has been converged. More...
bool	m_root
	Root if parallel. More...
bool	m_verbose
	Verbose. More...
bool	m_FlagWarnings
NekSysOperators	m_operator
	Operators. More...
int	m_SysDimen
	The dimension of the system. More...

Private Member Functions
NekDouble	CalcInexactNewtonForcing (const int &k, const NekDouble &resnormOld, const NekDouble &resnorm)

Friends
class	MemoryManager< NekNonlinSysNewton >
	Constructor for full direct matrix solve. More...

Detailed Description

Solves a nonlinear system using iterative methods.

Definition at line 46 of file NekNonlinSysNewton.h.

Constructor & Destructor Documentation

NekNonlinSysNewton()

Nektar::LibUtilities::NekNonlinSysNewton::NekNonlinSysNewton	(	const LibUtilities::SessionReaderSharedPtr &	pSession,
		const LibUtilities::CommSharedPtr &	vRowComm,
		const int	nscale,
		const NekSysKey &	pKey
	)

Definition at line 51 of file NekNonlinSysNewton.cpp.

    : NekNonlinSys(pSession, vRowComm, nscale, pKey)
{
}

~NekNonlinSysNewton()

Nektar::LibUtilities::NekNonlinSysNewton::~NekNonlinSysNewton ( )

overridedefault

Member Function Documentation

CalcInexactNewtonForcing()

NekDouble Nektar::LibUtilities::NekNonlinSysNewton::CalcInexactNewtonForcing ( const int &  k, const NekDouble &  resnormOld, const NekDouble &  resnorm  )

private

Definition at line 149 of file NekNonlinSysNewton.cpp.

{
    if (k == 0 || !m_InexactNewtonForcing)
    {
        return m_LinSysRelativeTolInNonlin;
    }
    else
    {
        NekDouble tmpForc =
            m_forcingGamma * pow((resnorm / resnormOld), m_forcingAlpha);
        return max(min(m_LinSysRelativeTolInNonlin, tmpForc), 1.0E-6);
    }
}

References m_forcingAlpha, m_forcingGamma, m_InexactNewtonForcing, and Nektar::LibUtilities::NekNonlinSys::m_LinSysRelativeTolInNonlin.

Referenced by v_SolveSystem().

create()

static NekNonlinSysSharedPtr Nektar::LibUtilities::NekNonlinSysNewton::create ( const LibUtilities::SessionReaderSharedPtr &  pSession, const LibUtilities::CommSharedPtr &  vRowComm, const int  nDimen, const NekSysKey &  pKey  )

inlinestatic

Definition at line 52 of file NekNonlinSysNewton.h.

    {
        NekNonlinSysSharedPtr p =
            MemoryManager<NekNonlinSysNewton>::AllocateSharedPtr(
                pSession, vRowComm, nDimen, pKey);
        p->InitObject();
        return p;
    }

References Nektar::MemoryManager< DataType >::AllocateSharedPtr(), and CellMLToNektar.cellml_metadata::p.

v_ConvergenceCheck()

bool Nektar::LibUtilities::NekNonlinSysNewton::v_ConvergenceCheck ( const int  nIteration, const Array< OneD, const NekDouble > &  Residual, const NekDouble  tol  )

overrideprotectedvirtual

Reimplemented from Nektar::LibUtilities::NekSys.

Definition at line 131 of file NekNonlinSysNewton.cpp.

{
    m_SysResNorm = Vmath::Dot(Residual.size(), Residual, Residual);
    m_rowComm->AllReduce(m_SysResNorm, Nektar::LibUtilities::ReduceSum);
 
    if (nIteration == 0)
    {
        m_SysResNorm0 = m_SysResNorm;
    }
 
    NekDouble resratio = m_SysResNorm / m_SysResNorm0;
    NekDouble restol   = m_NonlinIterTolRelativeL2;
 
    return resratio < restol * restol || m_SysResNorm < tol * tol;
}

References Vmath::Dot(), Nektar::LibUtilities::NekNonlinSys::m_NonlinIterTolRelativeL2, Nektar::LibUtilities::NekSys::m_rowComm, m_SysResNorm, m_SysResNorm0, and Nektar::LibUtilities::ReduceSum.

Referenced by v_SolveSystem().

v_InitObject()

void Nektar::LibUtilities::NekNonlinSysNewton::v_InitObject ( )

overrideprotectedvirtual

Reimplemented from Nektar::LibUtilities::NekNonlinSys.

Definition at line 59 of file NekNonlinSysNewton.cpp.

{
    NekSys::v_InitObject();
    m_Residual = Array<OneD, NekDouble>(m_SysDimen, 0.0);
    m_DeltSltn = Array<OneD, NekDouble>(m_SysDimen, 0.0);
}

References Nektar::LibUtilities::NekNonlinSys::m_DeltSltn, Nektar::LibUtilities::NekNonlinSys::m_Residual, Nektar::LibUtilities::NekSys::m_SysDimen, and Nektar::LibUtilities::NekSys::v_InitObject().

v_SetSysOperators()

void Nektar::LibUtilities::NekNonlinSysNewton::v_SetSysOperators ( const NekSysOperators &  in )

overrideprotectedvirtual

Reimplemented from Nektar::LibUtilities::NekSys.

Definition at line 66 of file NekNonlinSysNewton.cpp.

{
    NekSys::v_SetSysOperators(in);
    m_linsol->SetSysOperators(in);
}

References Nektar::LibUtilities::NekNonlinSys::m_linsol, and Nektar::LibUtilities::NekSys::v_SetSysOperators().

v_SolveSystem()

int Nektar::LibUtilities::NekNonlinSysNewton::v_SolveSystem ( const int  nGlobal, const Array< OneD, const NekDouble > &  pInput, Array< OneD, NekDouble > &  pOutput, const int  nDir, const NekDouble  tol, const NekDouble  factor  )

overrideprotectedvirtual

Reimplemented from Nektar::LibUtilities::NekSys.

Definition at line 75 of file NekNonlinSysNewton.cpp.

{
    ASSERTL0(nDir == 0, "nDir != 0 not tested");
    ASSERTL0(nGlobal == m_SysDimen, "nGlobal != m_SysDimen");
 
    int ntotal = nGlobal - nDir;
 
    m_SourceVec     = pInput;
    m_Solution      = pOutput;
    m_NtotLinSysIts = 0;
    m_converged     = false;
 
    Vmath::Vcopy(ntotal, pInput, 1, m_Solution, 1);
 
    NekDouble resnormOld = 0.0;
    int NttlNonlinIte    = 0;
    for (; NttlNonlinIte < m_maxiter; ++NttlNonlinIte)
    {
        m_operator.DoNekSysResEval(m_Solution, m_Residual);
 
        m_converged = v_ConvergenceCheck(NttlNonlinIte, m_Residual, tol);
        if (m_converged)
        {
            break;
        }
 
        NekDouble LinSysRelativeIteTol =
            CalcInexactNewtonForcing(NttlNonlinIte, resnormOld, m_SysResNorm);
        resnormOld = m_SysResNorm;
        m_linsol->setRhsMagnitude(m_SysResNorm);
        int ntmpLinSysIts = m_linsol->SolveSystem(
            ntotal, m_Residual, m_DeltSltn, 0, LinSysRelativeIteTol);
        m_NtotLinSysIts += ntmpLinSysIts;
 
        Vmath::Vsub(ntotal, m_Solution, 1, m_DeltSltn, 1, m_Solution, 1);
    }
 
    if (((!m_converged) || m_verbose) && m_root && m_FlagWarnings)
    {
        int nwidthcolm = 11;
 
        WARNINGL0(m_converged,
                  "     # Nonlinear solver not converge in DoImplicitSolve");
        cout << right << scientific << setw(nwidthcolm)
             << setprecision(nwidthcolm - 6)
             << "     * Newton-Its converged (RES=" << sqrt(m_SysResNorm)
             << " Res/(DtRHS): " << sqrt(m_SysResNorm / m_SysResNorm0)
             << " with " << setw(3) << NttlNonlinIte << " Non-Its)" << endl;
    }
 
    return NttlNonlinIte;
}

References ASSERTL0, CalcInexactNewtonForcing(), Nektar::LibUtilities::NekSysOperators::DoNekSysResEval(), Nektar::LibUtilities::NekSys::m_converged, Nektar::LibUtilities::NekNonlinSys::m_DeltSltn, Nektar::LibUtilities::NekSys::m_FlagWarnings, Nektar::LibUtilities::NekNonlinSys::m_linsol, Nektar::LibUtilities::NekSys::m_maxiter, Nektar::LibUtilities::NekNonlinSys::m_NtotLinSysIts, Nektar::LibUtilities::NekSys::m_operator, Nektar::LibUtilities::NekNonlinSys::m_Residual, Nektar::LibUtilities::NekSys::m_root, Nektar::LibUtilities::NekNonlinSys::m_Solution, Nektar::LibUtilities::NekNonlinSys::m_SourceVec, Nektar::LibUtilities::NekSys::m_SysDimen, m_SysResNorm, m_SysResNorm0, Nektar::LibUtilities::NekSys::m_verbose, tinysimd::sqrt(), v_ConvergenceCheck(), Vmath::Vcopy(), Vmath::Vsub(), and WARNINGL0.

Friends And Related Function Documentation

MemoryManager< NekNonlinSysNewton >

friend class MemoryManager< NekNonlinSysNewton >

friend

Constructor for full direct matrix solve.

Definition at line 1 of file NekNonlinSysNewton.h.

Member Data Documentation

className

string Nektar::LibUtilities::NekNonlinSysNewton::className

static

Initial value:

=
    LibUtilities::GetNekNonlinSysFactory().RegisterCreatorFunction(
        "Newton", NekNonlinSysNewton::create, "NekNonlinSysNewton solver.")

Definition at line 64 of file NekNonlinSysNewton.h.

m_forcingAlpha

NekDouble Nektar::LibUtilities::NekNonlinSysNewton::m_forcingAlpha = 0.5 * (1.0 + sqrt(5.0))

protected

Definition at line 78 of file NekNonlinSysNewton.h.

Referenced by CalcInexactNewtonForcing().

m_forcingGamma

NekDouble Nektar::LibUtilities::NekNonlinSysNewton::m_forcingGamma = 1.0

protected

Definition at line 77 of file NekNonlinSysNewton.h.

Referenced by CalcInexactNewtonForcing().

m_InexactNewtonForcing

bool Nektar::LibUtilities::NekNonlinSysNewton::m_InexactNewtonForcing = 0

protected

Definition at line 76 of file NekNonlinSysNewton.h.

Referenced by CalcInexactNewtonForcing().

m_SysResNorm

NekDouble Nektar::LibUtilities::NekNonlinSysNewton::m_SysResNorm

protected

Definition at line 74 of file NekNonlinSysNewton.h.

Referenced by v_ConvergenceCheck(), and v_SolveSystem().

m_SysResNorm0

NekDouble Nektar::LibUtilities::NekNonlinSysNewton::m_SysResNorm0

protected

Definition at line 73 of file NekNonlinSysNewton.h.

Referenced by v_ConvergenceCheck(), and v_SolveSystem().