ODESolver.H

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/*---------------------------------------------------------------------------*\
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  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | www.openfoam.com
     \\/     M anipulation  |
-------------------------------------------------------------------------------
    Copyright (C) 2011-2016 OpenFOAM Foundation
    Copyright (C) 2019 OpenCFD Ltd.
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.
 
    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.
 
    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
Class
    Foam::ODESolver
 
Group
    grpODESolvers
 
Description
    Abstract base-class for ODE system solvers
 
SourceFiles
    ODESolver.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef Foam_ODESolver_H
#define Foam_ODESolver_H
 
#include "ODESystem.H"
#include "typeInfo.H"
#include "autoPtr.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
 
/*---------------------------------------------------------------------------*\
                         Class ODESolver Declaration
\*---------------------------------------------------------------------------*/
 
class ODESolver
{
protected:
 
    // Protected Data
 
        //- Reference to ODESystem
        const ODESystem& odes_;
 
        //- Maximum size of the ODESystem
        const label maxN_;
 
        //- Size of the ODESystem (adjustable)
        mutable label n_;
 
        //- Absolute convergence tolerance per step
        scalarField absTol_;
 
        //- Relative convergence tolerance per step
        scalarField relTol_;
 
        //- The maximum number of sub-steps allowed for the integration step
        label maxSteps_;
 
 
    // Protected Member Functions
 
        //- Return the nomalized scalar error
        scalar normalizeError
        (
            const scalarField& y0,
            const scalarField& y,
            const scalarField& err
        ) const;
 
        //- No copy construct
        ODESolver(const ODESolver&) = delete;
 
        //- No copy assignment
        void operator=(const ODESolver&) = delete;
 
 
public:
 
    friend class ODESystem;
 
    //- Runtime type information
    TypeName("ODESolver");
 
    class stepState
    {
    public:
 
        const bool forward;
        scalar dxTry;
        scalar dxDid;
        bool first;
        bool last;
        bool reject;
        bool prevReject;
 
        stepState(const scalar dx)
        :
            forward(dx > 0 ? true : false),
            dxTry(dx),
            dxDid(0),
            first(true),
            last(false),
            reject(false),
            prevReject(false)
        {}
    };
 
 
    // Declare run-time constructor selection table
 
        declareRunTimeSelectionTable
        (
            autoPtr,
            ODESolver,
            dictionary,
            (const ODESystem& ode, const dictionary& dict),
            (ode, dict)
        );
 
 
    // Constructors
 
        //- Construct for given ODESystem
        ODESolver(const ODESystem& ode, const dictionary& dict);
 
        //- Construct for given ODESystem specifying tolerances
        ODESolver
        (
            const ODESystem& ode,
            const scalarField& absTol,
            const scalarField& relTol
        );
 
 
    // Selectors
 
        //- Select null constructed
        static autoPtr<ODESolver> New
        (
            const ODESystem& ode,
            const dictionary& dict
        );
 
 
    //- Destructor
    virtual ~ODESolver() = default;
 
 
    // Member Functions
 
        //- The number of equations to solve
        label nEqns() const noexcept { return n_; }
 
        //- Access to the absolute tolerance field
        scalarField& absTol() noexcept { return absTol_; }
 
        //- Access to the relative tolerance field
        scalarField& relTol() noexcept { return relTol_; }
 
        //- Resize the ODE solver
        virtual bool resize() = 0;
 
        template<class Type>
        static inline void resizeField(UList<Type>& f, const label n);
 
        template<class Type>
        inline void resizeField(UList<Type>& f) const;
 
        inline void resizeMatrix(scalarSquareMatrix& m) const;
 
        //- Solve the ODE system as far as possible up to dxTry
        //  adjusting the step as necessary to provide a solution within
        //  the specified tolerance.
        //  Update the state and return an estimate for the next step in dxTry
        virtual void solve
        (
            scalar& x,
            scalarField& y,
            scalar& dxTry
        ) const;
 
        //- Solve the ODE system as far as possible up to dxTry
        //  adjusting the step as necessary to provide a solution within
        //  the specified tolerance.
        //  Update the state and return an estimate for the next step in dxTry
        virtual void solve
        (
            scalar& x,
            scalarField& y,
            stepState& step
        ) const;
 
        //- Solve the ODE system from xStart to xEnd, update the state
        //  and return an estimate for the next step in dxTry
        virtual void solve
        (
            const scalar xStart,
            const scalar xEnd,
            scalarField& y,
            scalar& dxEst
        ) const;
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#include "ODESolverI.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //