RK4Integrator.hpp

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#pragma once

 
#include <icarus/sim/integrators/Integrator.hpp>
#include <janus/math/IntegratorStep.hpp>
 
namespace icarus {
 
// =============================================================================
// Forward Euler Integrator (1st Order)
// =============================================================================

template <typename Scalar> class EulerIntegrator : public Integrator<Scalar> {
  public:
    using typename Integrator<Scalar>::DerivativeFunc;
 
    JanusVector<Scalar> Step(const DerivativeFunc &f, const JanusVector<Scalar> &x, Scalar t,
                             Scalar dt) override {
        return janus::euler_step(f, x, t, dt);
    }
 
    [[nodiscard]] std::string Name() const override { return "Euler"; }
    [[nodiscard]] int Order() const override { return 1; }
    [[nodiscard]] IntegratorType Type() const override { return IntegratorType::Euler; }
};
 
// =============================================================================
// Heun's Method / RK2 Integrator (2nd Order)
// =============================================================================

template <typename Scalar> class RK2Integrator : public Integrator<Scalar> {
  public:
    using typename Integrator<Scalar>::DerivativeFunc;
 
    JanusVector<Scalar> Step(const DerivativeFunc &f, const JanusVector<Scalar> &x, Scalar t,
                             Scalar dt) override {
        return janus::rk2_step(f, x, t, dt);
    }
 
    [[nodiscard]] std::string Name() const override { return "RK2"; }
    [[nodiscard]] int Order() const override { return 2; }
    [[nodiscard]] IntegratorType Type() const override { return IntegratorType::RK2; }
};
 
// =============================================================================
// Classic RK4 Integrator (4th Order)
// =============================================================================

template <typename Scalar> class RK4Integrator : public Integrator<Scalar> {
  public:
    using typename Integrator<Scalar>::DerivativeFunc;
 
    JanusVector<Scalar> Step(const DerivativeFunc &f, const JanusVector<Scalar> &x, Scalar t,
                             Scalar dt) override {
        return janus::rk4_step(f, x, t, dt);
    }
 
    [[nodiscard]] std::string Name() const override { return "RK4"; }
    [[nodiscard]] int Order() const override { return 4; }
    [[nodiscard]] IntegratorType Type() const override { return IntegratorType::RK4; }
};
 
} // namespace icarus