NekNonlinSysIterNewtonBacktrack.h

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///////////////////////////////////////////////////////////////////////////////
//
// File: NekNonlinSysIterNewtonBacktrack.h
//
// For more information, please see: http://www.nektar.info
//
// The MIT License
//
// Copyright (c) 2006 Division of Applied Mathematics, Brown University (USA),
// Department of Aeronautics, Imperial College London (UK), and Scientific
// Computing and Imaging Institute, University of Utah (USA).
//
// License for the specific language governing rights and limitations under
// Permission is hereby granted, free of charge, to any person obtaining a
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// Software is furnished to do so, subject to the following conditions:
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// Description: NekNonlinSysIterNewtonBacktrack header
//
///////////////////////////////////////////////////////////////////////////////
 
#ifndef NEKTAR_LIB_UTILITIES_LINEAR_ALGEBRA_NEK_NONLINSYS_NEWTON_BACKTRACK_H
#define NEKTAR_LIB_UTILITIES_LINEAR_ALGEBRA_NEK_NONLINSYS_NEWTON_BACKTRACK_H
 
#include <LibUtilities/LinearAlgebra/NekNonlinSysIterNewton.h>
 
namespace Nektar::LibUtilities
{
 
class NekNonlinSysIterNewtonBacktrack : public NekNonlinSysIterNewton
{
public:
    friend class MemoryManager<NekNonlinSysIterNewtonBacktrack>;
 
    LIB_UTILITIES_EXPORT static NekNonlinSysIterSharedPtr create(
        const LibUtilities::SessionReaderSharedPtr &pSession,
        const LibUtilities::CommSharedPtr &vComm, const int nDimen,
        const NekSysKey &pKey)
    {
        NekNonlinSysIterSharedPtr p =
            MemoryManager<NekNonlinSysIterNewtonBacktrack>::AllocateSharedPtr(
                pSession, vComm, nDimen, pKey);
        p->InitObject();
        return p;
    }
 
    static std::string className;
 
    LIB_UTILITIES_EXPORT NekNonlinSysIterNewtonBacktrack(
        const LibUtilities::SessionReaderSharedPtr &pSession,
        const LibUtilities::CommSharedPtr &vComm, const int nDimen,
        const NekSysKey &pKey);
 
    LIB_UTILITIES_EXPORT ~NekNonlinSysIterNewtonBacktrack() override = default;
 
protected:
    NekDouble m_newtonScaleInit       = 1.0e-2;
    NekDouble m_newtonScaleMax        = 1.0e-1;
    NekDouble m_newtonScaleMin        = 1.0e-6;
    NekDouble m_newtonScaleGrowFactor = 2.0;
    NekDouble m_backtrackFactor       = 0.5;
    int m_maxBacktrackSteps           = 4;
    NekDouble m_acceptReductionEta    = 1.0e-4;
 
    Array<OneD, NekDouble> m_solutionTrial;
    Array<OneD, NekDouble> m_residualTrial;
 
    void v_InitObject() override;
 
    bool v_ApplyNewtonUpdate(const int ntotal,
                             const NekDouble oldResNorm) override;
};
 
} // namespace Nektar::LibUtilities
 
#endif