linearFunction.hpp

#ifndef ABLATELIBRARY_LINEARFUNCTION_FUNCTION_HPP
#define ABLATELIBRARY_LINEARFUNCTION_FUNCTION_HPP
#include <muParser.h>
#include "formulaBase.hpp"
 
namespace ablate::mathFunctions {
class LinearFunction : public MathFunction {
   private:
    std::shared_ptr<MathFunction> startFunction;
    std::shared_ptr<MathFunction> endFunction;
    const double start;
    const double end;
    const int dir;
 
    static PetscErrorCode LinearFunctionPetscFunction(PetscInt dim, PetscReal time, const PetscReal x[], PetscInt Nf, PetscScalar* u, void* ctx);
 
    inline static double Interpolate(double x, double x0, double x1, double y0, double y1) {
        if (x < x0) {
            return y0;
        } else if (x > x1) {
            return y1;
        }
 
        return y0 + (x - x0) * (y1 - y0) / (x1 - x0);
    }
 
    inline double DetermineDirectionValue(double x, double y, double z) const {
        switch (dir) {
            case 0:
                return x;
            case 1:
                return y;
            case 2:
                return z;
            default:
                return x;
        }
    }
 
   public:
    LinearFunction(const LinearFunction&) = delete;
    void operator=(const LinearFunction&) = delete;
 
    explicit LinearFunction(std::shared_ptr<MathFunction> startFunction, std::shared_ptr<MathFunction> endFunction, double start, double end, int dir);
 
    double Eval(const double& x, const double& y, const double& z, const double& t) const override;
 
    double Eval(const double* xyz, const int& ndims, const double& t) const override;
 
    void Eval(const double& x, const double& y, const double& z, const double& t, std::vector<double>& result) const override;
 
    void Eval(const double* xyz, const int& ndims, const double& t, std::vector<double>& result) const override;
 
    void* GetContext() override { return this; }
 
    PetscFunction GetPetscFunction() override { return LinearFunctionPetscFunction; }
};
}  // namespace ablate::mathFunctions
 
#endif  // ABLATELIBRARY_SIMPLEFORMULA_HPP