diagnostics.hpp

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#pragma once

 
#include <span>
 
#include "orrery/core/particle_data.hpp"
#include "orrery/core/softening.hpp"
#include "orrery/core/types.hpp"
#include "orrery/core/vec3.hpp"
#include "orrery/core/vec3_span.hpp"
 
namespace orrery::core {

struct Diagnostics {
    Real kinetic_energy{};
    Real potential_energy{};
    Vec3 linear_momentum{};
    Vec3 angular_momentum{};
 
    [[nodiscard]] constexpr Real total_energy() const noexcept {
        return kinetic_energy + potential_energy;
    }

    [[nodiscard]] constexpr Real virial_ratio() const noexcept {
        const Real magnitude = potential_energy < 0 ? -potential_energy : potential_energy;
        return 2 * kinetic_energy / magnitude;
    }
};

[[nodiscard]] Real total_mass(std::span<const Real> masses);

[[nodiscard]] Vec3 centre_of_mass(Vec3Span<const Real> positions, std::span<const Real> masses);

[[nodiscard]] Vec3 centre_of_mass_velocity(Vec3Span<const Real> velocities,
                                           std::span<const Real> masses);

[[nodiscard]] Real kinetic_energy(Vec3Span<const Real> velocities, std::span<const Real> masses);

[[nodiscard]] Real potential_energy(Vec3Span<const Real> positions, std::span<const Real> masses,
                                    Softening softening);

[[nodiscard]] Vec3 linear_momentum(Vec3Span<const Real> velocities, std::span<const Real> masses);

[[nodiscard]] Vec3 angular_momentum(Vec3Span<const Real> positions, Vec3Span<const Real> velocities,
                                    std::span<const Real> masses);

[[nodiscard]] Diagnostics measure_diagnostics(const ParticleData& data, Softening softening);
 
} // namespace orrery::core