Detailed Description

Definition at line 19 of file CubicRoots.h.

#include <CubicRoots.h>

Public Member Functions
	CubicSolver (const double a, const double b, const double c, const double d)
std::vector< double >	solve ()
double	smallestPositiveRealRoot ()

Private Attributes
double	a_
double	b_
double	c_
double	d_

Constructor & Destructor Documentation

◆ CubicSolver()

MathLib::CubicSolver::CubicSolver	(	const double	a,
		const double	b,
		const double	c,
		const double	d )

inline

Definition at line 22 of file CubicRoots.h.

        : a_(a), b_(b), c_(c), d_(d)
    {
        if (std::abs(a_) < 1e-9)
        {
            OGS_FATAL("'a' must be non-zero for a cubic equation.");
        }
    }

References a_, b_, c_, d_, and OGS_FATAL.

Member Function Documentation

◆ smallestPositiveRealRoot()

double MathLib::CubicSolver::smallestPositiveRealRoot ( )

inline

Definition at line 62 of file CubicRoots.h.

    {
        std::vector<double> const roots = solve();
 
        auto positive_roots =
            roots | ranges::views::filter([](double root) { return root > 0; });
 
        // If no positive root exists, return NaN
        if (ranges::empty(positive_roots))
        {
            return std::numeric_limits<double>::quiet_NaN();
        }
 
        return ranges::min(positive_roots);
    }

References solve().

Referenced by MaterialPropertyLib::PengRobinson::value().

◆ solve()

std::vector< double > MathLib::CubicSolver::solve ( )

inline

Definition at line 31 of file CubicRoots.h.

    {
        std::array<double, 3> const roots =
            boost::math::tools::cubic_roots<double>(a_, b_, c_, d_);
 
        std::vector<double> adjusted_roots;
        adjusted_roots.reserve(3);
 
        double last_valid = std::numeric_limits<double>::quiet_NaN();
 
        for (auto root : roots)
        {
            if (std::isnan(root))
            {
                if (!std::isnan(last_valid))
                {
                    adjusted_roots.push_back(last_valid);
                }
                // If we get NaN before any valid root, we just skip it
            }
            else
            {
                adjusted_roots.push_back(root);
                last_valid = root;
            }
        }
 
        ranges::sort(adjusted_roots);
        return adjusted_roots;
    }