rodas23.H

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License
    This file is part of OpenFOAM.

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Class
    Foam::rodas23

Description
    L-stable, stiffly-accurate embedded Rosenbrock ODE solver of order (2)3.

    References:
    \verbatim
        Sandu et al,
        "Benchmarking stiff ODE solvers for atmospheric chemistry problems II
         Rosenbrock solvers",
         A. Sandu,
         J.G. Verwer,
         J.G. Blom,
         E.J. Spee,
         G.R. Carmichael,
         F.A. Potra,
         Atmospheric Environment, Volume 31, 1997, Issue 20, Pages 3459-3472
    \endverbatim

SourceFiles
    rodas23.C

\*---------------------------------------------------------------------------*/

#ifndef rodas23_H
#define rodas23_H

#include "ODESolver.H"
#include "adaptiveSolver.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{

/*---------------------------------------------------------------------------*\
                           Class rodas23 Declaration
\*---------------------------------------------------------------------------*/

class rodas23
:
    public ODESolver,
    public adaptiveSolver
{
    // Private data

        mutable scalarField k1_;
        mutable scalarField k2_;
        mutable scalarField k3_;
        mutable scalarField dy_;
        mutable scalarField err_;
        mutable scalarField dydx_;
        mutable scalarField dfdx_;
        mutable scalarSquareMatrix dfdy_;
        mutable scalarSquareMatrix a_;
        mutable labelList pivotIndices_;

        static const scalar
            c3,
            d1, d2,
            a31,
            a41,
            c21, c31, c32,
            c41, c42, c43,
            gamma;

public:

    //- Runtime type information
    TypeName("rodas23");


    // Constructors

        //- Construct from ODE
        rodas23(const ODESystem& ode, const dictionary& dict);


    // Member Functions

        //- Inherit solve from ODESolver
        using ODESolver::solve;

        //- Solve a single step dx and return the error
        scalar solve
        (
            const scalar x0,
            const scalarField& y0,
            const scalarField& dydx0,
            const scalar dx,
            scalarField& y
        ) const;

        //- Solve the ODE system and the update the state
        void solve
        (
            scalar& x,
            scalarField& y,
            scalar& dxTry
        ) const;
};


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace Foam

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#endif

// ************************************************************************* //