ode

ODE

ode::Function

The function for an ODE solver needs to provide the derivative (1st and optional 2nd oder) of an equation with the methods derive and derive2.

The parameters are given in a single vector. The setParams and getParams methods implement the mapping of the parameters since the solver just iterates of the given vector.

ode::Solver

The ODE solver provides an interface for certain implementation´s.

Example

Solve f(x) = sin(x) with f'(x) = cos(x) by using the Euler algorithm.

#include "ode/Euler.h"
#include <cmath>
#include <iostream>

using Vector = ode::Vector<float_t>;
using Function = ode::Function<float_t>;
using Euler = ode::Euler<float_t>;

class Derivative : public Function
{
public:
    Derivative()
        : m_data(1u)
    {
    }

    Vector derive(float_t x, [[maybe_unused]] Vector& y) final
    {
        return Vector{std::cos(x)};
    }

    Vector getParams() const final
    {
        return m_data;
    }

    void setParams(const Vector& y) final
    {
        m_data += y;
    }

private:
    Vector m_data;
};

int main(int argc, char** argv)
{
    static constexpr float_t dt{0.001F};

    Euler euler{};
    Derivative y{};

    for (float_t t{0.0F}; t < 1.F; t += dt)
    {
        euler.calc(t, dt, y);
        std::cout << t << "," << y.getParams()[0u] << "," << std::sin(x) << std::endl;
    }
}