/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 2011-2016 OpenFOAM Foundation
     \\/     M anipulation  |
-------------------------------------------------------------------------------
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::polynomialFunction

Description
    Polynomial function representation

    \verbatim
        poly = logCoeff*log(x) + sum(coeffs[i]*x^i)
    \endverbatim

    where <tt> 0 <= i <= N </tt>

    - integer powers, starting at zero
    - \c value(x) to evaluate the poly for a given value
    - \c integrate(x1, x2) between two scalar values
    - \c integral() to return a new, integral coeff polynomial
      - increases the size (order)
    - \c integralMinus1() to return a new, integral coeff polynomial where
      the base poly starts at order -1

See also
    Foam::Polynomial for a templated implementation

SourceFiles
    polynomialFunction.C

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

#ifndef polynomialFunction_H
#define polynomialFunction_H

#include "scalarList.H"
#include "Ostream.H"
#include "runTimeSelectionTables.H"

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

namespace Foam
{

// Forward declaration of classes
class polynomialFunction;

// Forward declaration of friend functions
Ostream& operator<<(Ostream&, const polynomialFunction&);


/*---------------------------------------------------------------------------*\
                     Class polynomialFunction Declaration
\*---------------------------------------------------------------------------*/

class polynomialFunction
:
    private scalarList
{
    // Private data

        //- Include the log term? - only activated using integralMinus1()
        bool logActive_;

        //- Log coefficient - only activated using integralMinus1()
        scalar logCoeff_;


    // Private Member Functions

        //- Return integral coefficients.
        //  Argument becomes zeroth element (constant of integration)
        static polynomialFunction cloneIntegral
        (
            const polynomialFunction&,
            const scalar intConstant = 0.0
        );

        //- Return integral coefficients when lowest order is -1.
        //  Argument becomes zeroth element (constant of integration)
        static polynomialFunction cloneIntegralMinus1
        (
            const polynomialFunction&,
            const scalar intConstant = 0.0
        );


        //- Disallow default bitwise assignment
        void operator=(const polynomialFunction&);



public:

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


    // Constructors

        //- Construct a particular size, with all coefficients = 0.0
        explicit polynomialFunction(const label);

        //- Copy constructor
        polynomialFunction(const polynomialFunction&);

        //- Construct from a list of coefficients
        explicit polynomialFunction(const UList<scalar>& coeffs);

        //- Construct from Istream
        polynomialFunction(Istream&);


    //- Destructor
    virtual ~polynomialFunction();


    // Member Functions

            //- Return the number of coefficients
            using scalarList::size;

            //- Return coefficient
            using scalarList::operator[];


        // Access


            //- Return true if the log term is active
            bool logActive() const;

            //- Return the log coefficient
            scalar logCoeff() const;


        // Evaluation

            //- Return polynomial value
            scalar value(const scalar x) const;

            //- Integrate between two values
            scalar integrate(const scalar x1, const scalar x2) const;


            //- Return integral coefficients.
            //  Argument becomes zeroth element (constant of integration)
            polynomialFunction integral
            (
                const scalar intConstant = 0.0
            ) const;

            //- Return integral coefficients when lowest order is -1.
            //  Argument becomes zeroth element (constant of integration)
            polynomialFunction integralMinus1
            (
                const scalar intConstant = 0.0
            ) const;


    // Member Operators

        polynomialFunction& operator+=(const polynomialFunction&);
        polynomialFunction& operator-=(const polynomialFunction&);

        polynomialFunction& operator*=(const scalar);
        polynomialFunction& operator/=(const scalar);


    //- Ostream Operator
    friend Ostream& operator<<(Ostream&, const polynomialFunction&);
};


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

// * * * * * * * * * * * * * * * Global Operators  * * * * * * * * * * * * * //

polynomialFunction operator+
(
    const polynomialFunction&,
    const polynomialFunction&
);


polynomialFunction operator-
(
    const polynomialFunction&,
    const polynomialFunction&
);


polynomialFunction operator*
(
    const scalar,
    const polynomialFunction&
);


polynomialFunction operator/
(
    const scalar,
    const polynomialFunction&
);


polynomialFunction operator*
(
    const polynomialFunction&,
    const scalar
);


polynomialFunction operator/
(
    const polynomialFunction&,
    const scalar
);


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

} // End namespace Foam

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

#endif

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