siderust 0.6.0

High-precision astronomy and satellite mechanics in Rust.
Documentation 
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// SPDX-License-Identifier: AGPL-3.0-or-later
// Copyright (C) 2026 Vallés Puig, Ramon

// ────────────────────────────────────────────────────────────────────────────
// Main term of the lunar theory (ELP “Main Problem” series).
// Each record governs one sine term of the form:
//
//   Δλ = a * sin( Σ ilu[i] * Φ_i  +  Σ b[j] * T^j )
//
// where
//   Φ_i  = {D, M, M′, F}  → the four fundamental lunar arguments
//   T     = Julian millennia from J2000 (ΔT = (JD − 2451545.0)/365250)
//   b[j]  = time polynomial coefficients (constant, linear, … 5th-order)
//
// All amplitudes are usually given in 0.0001″ (10⁻⁴ arc-sec).
// ────────────────────────────────────────────────────────────────────────────
pub struct MainProblem {
    /// Integer multipliers of the fundamental arguments
    /// in the order [D, M, M′, F].
    pub ilu: [i64; 4],

    /// Sine amplitude ‘a’ (10⁻⁴ arc-seconds).
    pub a: f64,

    /// Time‐polynomial coefficients b₀…b₅ for the phase argument:
    ///   φ = Σ (ilu[i]·Φ_i)  +  (b₀ + b₁ T + ⋯ + b₅ T⁵)
    pub b: [f64; 6],
}

// ────────────────────────────────────────────────────────────────────────────
// Earth–Moon specific perturbations (ELP Earth Perturbation series).
// A term contributes
//
//   Δλ = a · T^iz · sin( Σ ilu[i] * Φ_i  +  p  +  o·T )
//
//   iz   = real exponent of T (often 0, 1, or −1)
//   o    = secular rate in the phase (radians per Julian millennia)
//   p    = phase offset at T = 0
// ────────────────────────────────────────────────────────────────────────────
#[allow(dead_code)]
pub struct EarthPert {
    /// Exponent ‘iz’ of the time factor T^iz.
    pub iz: f64,

    /// Integer multipliers for [D, M, M′, F].
    pub ilu: [i64; 4],

    /// Linear phase rate ‘o’ (radians / Julian millennia).
    pub o: f64,

    /// Amplitude ‘a’ (10⁻⁴ arc-seconds).
    pub a: f64,

    /// Constant phase offset ‘p’ (radians) at epoch J2000.
    pub p: f64,
}

// ────────────────────────────────────────────────────────────────────────────
// Planetary perturbations acting on the Moon
// (ELP Planetary Perturbation series).
// Each term is:
//
//   Δλ = θ · sin( Σ ipla[k] * Π_k  +  p  +  o·T )
//
//   Π_k  = 11 planetary arguments (L_ME, L_VE, …, L_NE, D, M, M′)
//   θ    = amplitude (arc-seconds)
//   o    = secular rate in phase
//   p    = phase offset
// ────────────────────────────────────────────────────────────────────────────
#[allow(dead_code)]
pub struct PlanetPert {
    /// Integer multipliers for the 11 planetary arguments Π_k
    /// (Mercury → Neptune plus three lunar/solar combinations).
    pub ipla: [i64; 11],

    /// Amplitude ‘θ’ (10⁻⁴ arc-seconds).
    pub theta: f64,

    /// Linear phase rate ‘o’ (radians / Julian millennia).
    pub o: f64,

    /// Constant phase offset ‘p’ (radians) at epoch J2000.
    pub p: f64,
}