linearEqnI.H

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// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
inline Foam::linearEqn::linearEqn()
{}
 
 
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::a() const
{
    return this->v_[A];
}
 
 
inline Foam::scalar Foam::linearEqn::b() const
{
    return this->v_[B];
}
 
 
inline Foam::scalar& Foam::linearEqn::a()
{
    return this->v_[A];
}
 
 
inline Foam::scalar& Foam::linearEqn::b()
{
    return this->v_[B];
}
 
 
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
{
    /*
 
    This function solves a linear equation of the following form:
 
        a*x + b = 0
          x + B = 0
 
    */
 
    const scalar a = this->a();
    const scalar b = this->b();
 
    if (a == 0)
    {
        return Roots<1>(roots::nan, 0);
    }
 
    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);
}
 
 
// ************************************************************************* //