linearEqnI.H

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// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //

inline Foam::linearEqn::linearEqn(const Foam::zero)
:
    VectorSpace<linearEqn, scalar, 2>(Foam::zero{})
{}


inline Foam::linearEqn::linearEqn(const scalar a, const scalar b)
{
    this->v_[A] = a;
    this->v_[B] = b;
}


// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //

inline Foam::scalar Foam::linearEqn::value(const scalar x) const
{
    return x*a() + b();
}


inline Foam::scalar Foam::linearEqn::derivative(const scalar x) const
{
    return a();
}


inline Foam::scalar Foam::linearEqn::error(const scalar x) const
{
    return SMALL*(mag(x*a()) + mag(b()));
}


inline Foam::Roots<1> Foam::linearEqn::roots() const
{
    const scalar a = this->a();
    const scalar b = this->b();

    if (mag(a) < VSMALL)
    {
        return Roots<1>(roots::nan, 0);
    }
    else if (mag(b/VGREAT) >= mag(a))
    {
        return Roots<1>(sign(a) == sign(b) ? roots::negInf : roots::posInf, 0);
    }

    return Roots<1>(roots::real, -b/a);
}


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