'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

var base = require('./base.cjs');
var sexagesimal = require('./sexagesimal.cjs');

/**
 * @copyright 2013 Sonia Keys
 * @copyright 2016 commenthol
 * @license MIT
 * @module nutation
 */

// Nutation: Chapter 22, Nutation and the Obliquity of the Ecliptic.

/**
 * Nutation returns nutation in longitude (Δψ) and nutation in obliquity (Δε)
 * for a given JDE.
 *
 * JDE = UT + ΔT, see package.
 *
 * Computation is by 1980 IAU theory, with terms < .0003″ neglected.
 *
 * Result units are radians.
 *
 * @param {number} jde - Julian ephemeris day
 * @return {number[]} [Δψ, Δε] - [longitude, obliquity] in radians
 */
function nutation (jde) {
  const T = base["default"].J2000Century(jde);
  // Mean elongation of the Moon from the sun
  const D = base["default"].horner(T,
    297.85036, 445267.11148, -0.0019142, 1.0 / 189474) * Math.PI / 180;
  // Mean anomaly of the Sun (Earth)
  const M = base["default"].horner(T,
    357.52772, 35999.050340, -0.0001603, -1.0 / 300000) * Math.PI / 180;
  // Mean anomaly of the Moon
  const N = base["default"].horner(T,
    134.96298, 477198.867398, 0.0086972, 1.0 / 56250) * Math.PI / 180;
  // Moon's argument of latitude
  const F = base["default"].horner(T,
    93.27191, 483202.017538, -0.0036825, 1.0 / 327270) * Math.PI / 180;
  // Longitude of the ascending node of the Moon's mean orbit on the ecliptic, measured from mean equinox of date
  const Ω = base["default"].horner(T,
    125.04452, -1934.136261, 0.0020708, 1.0 / 450000) * Math.PI / 180;
  let Δψ = 0;
  let Δε = 0;
  // sum in reverse order to accumulate smaller terms first
  for (let i = table22A.length - 1; i >= 0; i--) {
    const row = table22A[i];
    const arg = row.d * D + row.m * M + row.n * N + row.f * F + row.ω * Ω;
    const [s, c] = base["default"].sincos(arg);
    Δψ += s * (row.s0 + row.s1 * T);
    Δε += c * (row.c0 + row.c1 * T);
  }
  Δψ *= 0.0001 / 3600 * (Math.PI / 180);
  Δε *= 0.0001 / 3600 * (Math.PI / 180);
  return [Δψ, Δε] // (Δψ, Δε float)
}
/**
 * ApproxNutation returns a fast approximation of nutation in longitude (Δψ)
 * and nutation in obliquity (Δε) for a given JDE.
 *
 * Accuracy is 0.5″ in Δψ, 0.1″ in Δε.
 *
 * Result units are radians.
 *
 * @param {number} jde - Julian ephemeris day
 * @return {number[]} [Δψ, Δε] - [longitude, obliquity] in radians
 */
function approxNutation (jde) {
  const T = (jde - base["default"].J2000) / 36525;
  const Ω = (125.04452 - 1934.136261 * T) * Math.PI / 180;
  const L = (280.4665 + 36000.7698 * T) * Math.PI / 180;
  const N = (218.3165 + 481267.8813 * T) * Math.PI / 180;
  const [sΩ, cΩ] = base["default"].sincos(Ω);
  const [s2L, c2L] = base["default"].sincos(2 * L);
  const [s2N, c2N] = base["default"].sincos(2 * N);
  const [s2Ω, c2Ω] = base["default"].sincos(2 * Ω);
  const Δψ = (-17.2 * sΩ - 1.32 * s2L - 0.23 * s2N + 0.21 * s2Ω) / 3600 * (Math.PI / 180);
  const Δε = (9.2 * cΩ + 0.57 * c2L + 0.1 * c2N - 0.09 * c2Ω) / 3600 * (Math.PI / 180);
  return [Δψ, Δε] // (Δψ, Δε float)
}

/**
 * MeanObliquity returns mean obliquity (ε₀) following the IAU 1980
 * polynomial.
 *
 * Accuracy is 1″ over the range 1000 to 3000 years and 10″ over the range
 * 0 to 4000 years.
 *
 * Result unit is radians.
 *
 * @param {number} jde - Julian ephemeris day
 * @return {number} mean obliquity (ε₀)
 */
function meanObliquity (jde) {
  // (22.2) p. 147
  return base["default"].horner(
    base["default"].J2000Century(jde),
    new sexagesimal["default"].Angle(false, 23, 26, 21.448).rad(),
    -46.815 / 3600 * (Math.PI / 180),
    -0.00059 / 3600 * (Math.PI / 180),
    0.001813 / 3600 * (Math.PI / 180)
  )
}

/**
 * MeanObliquityLaskar returns mean obliquity (ε₀) following the Laskar
 * 1986 polynomial.
 *
 * Accuracy over the range 1000 to 3000 years is .01″.
 *
 * Accuracy over the valid date range of -8000 to +12000 years is
 * "a few seconds."
 *
 * Result unit is radians.
 *
 * @param {number} jde - Julian ephemeris day
 * @return {number} mean obliquity (ε₀)
 */
function meanObliquityLaskar (jde) {
  // (22.3) p. 147
  return base["default"].horner(
    base["default"].J2000Century(jde) * 0.01,
    new sexagesimal["default"].Angle(false, 23, 26, 21.448).rad(),
    -4680.93 / 3600 * (Math.PI / 180),
    -1.55 / 3600 * (Math.PI / 180),
    1999.25 / 3600 * (Math.PI / 180),
    -51.38 / 3600 * (Math.PI / 180),
    -249.67 / 3600 * (Math.PI / 180),
    -39.05 / 3600 * (Math.PI / 180),
    7.12 / 3600 * (Math.PI / 180),
    27.87 / 3600 * (Math.PI / 180),
    5.79 / 3600 * (Math.PI / 180),
    2.45 / 3600 * (Math.PI / 180)
  )
}

/**
 * NutationInRA returns "nutation in right ascension" or "equation of the
 * equinoxes."
 *
 * Result is an angle in radians.
 *
 * @param {number} jde - Julian ephemeris day
 * @return {number} nutation in right ascension
 */
function nutationInRA (jde) {
  const [Δψ, Δε] = nutation(jde);
  const ε0 = meanObliquity(jde);
  return Δψ * Math.cos(ε0 + Δε)
}

const table22A = (function () {
  const PROPS = 'd,m,n,f,ω,s0,s1,c0,c1'.split(',');
  const tab = [
    [0, 0, 0, 0, 1, -171996, -174.2, 92025, 8.9],
    [-2, 0, 0, 2, 2, -13187, -1.6, 5736, -3.1],
    [0, 0, 0, 2, 2, -2274, -0.2, 977, -0.5],
    [0, 0, 0, 0, 2, 2062, 0.2, -895, 0.5],
    [0, 1, 0, 0, 0, 1426, -3.4, 54, -0.1],
    [0, 0, 1, 0, 0, 712, 0.1, -7, 0],
    [-2, 1, 0, 2, 2, -517, 1.2, 224, -0.6],
    [0, 0, 0, 2, 1, -386, -0.4, 200, 0],
    [0, 0, 1, 2, 2, -301, 0, 129, -0.1],
    [-2, -1, 0, 2, 2, 217, -0.5, -95, 0.3],
    [-2, 0, 1, 0, 0, -158, 0, 0, 0],
    [-2, 0, 0, 2, 1, 129, 0.1, -70, 0],
    [0, 0, -1, 2, 2, 123, 0, -53, 0],
    [2, 0, 0, 0, 0, 63, 0, 0, 0],
    [0, 0, 1, 0, 1, 63, 0.1, -33, 0],
    [2, 0, -1, 2, 2, -59, 0, 26, 0],
    [0, 0, -1, 0, 1, -58, -0.1, 32, 0],
    [0, 0, 1, 2, 1, -51, 0, 27, 0],
    [-2, 0, 2, 0, 0, 48, 0, 0, 0],
    [0, 0, -2, 2, 1, 46, 0, -24, 0],
    [2, 0, 0, 2, 2, -38, 0, 16, 0],
    [0, 0, 2, 2, 2, -31, 0, 13, 0],
    [0, 0, 2, 0, 0, 29, 0, 0, 0],
    [-2, 0, 1, 2, 2, 29, 0, -12, 0],
    [0, 0, 0, 2, 0, 26, 0, 0, 0],
    [-2, 0, 0, 2, 0, -22, 0, 0, 0],
    [0, 0, -1, 2, 1, 21, 0, -10, 0],
    [0, 2, 0, 0, 0, 17, -0.1, 0, 0],
    [2, 0, -1, 0, 1, 16, 0, -8, 0],
    [-2, 2, 0, 2, 2, -16, 0.1, 7, 0],
    [0, 1, 0, 0, 1, -15, 0, 9, 0],
    [-2, 0, 1, 0, 1, -13, 0, 7, 0],
    [0, -1, 0, 0, 1, -12, 0, 6, 0],
    [0, 0, 2, -2, 0, 11, 0, 0, 0],
    [2, 0, -1, 2, 1, -10, 0, 5, 0],
    [2, 0, 1, 2, 2, -8, 0, 3, 0],
    [0, 1, 0, 2, 2, 7, 0, -3, 0],
    [-2, 1, 1, 0, 0, -7, 0, 0, 0],
    [0, -1, 0, 2, 2, -7, 0, 3, 0],
    [2, 0, 0, 2, 1, -7, 0, 3, 0],
    [2, 0, 1, 0, 0, 6, 0, 0, 0],
    [-2, 0, 2, 2, 2, 6, 0, -3, 0],
    [-2, 0, 1, 2, 1, 6, 0, -3, 0],
    [2, 0, -2, 0, 1, -6, 0, 3, 0],
    [2, 0, 0, 0, 1, -6, 0, 3, 0],
    [0, -1, 1, 0, 0, 5, 0, 0, 0],
    [-2, -1, 0, 2, 1, -5, 0, 3, 0],
    [-2, 0, 0, 0, 1, -5, 0, 3, 0],
    [0, 0, 2, 2, 1, -5, 0, 3, 0],
    [-2, 0, 2, 0, 1, 4, 0, 0, 0],
    [-2, 1, 0, 2, 1, 4, 0, 0, 0],
    [0, 0, 1, -2, 0, 4, 0, 0, 0],
    [-1, 0, 1, 0, 0, -4, 0, 0, 0],
    [-2, 1, 0, 0, 0, -4, 0, 0, 0],
    [1, 0, 0, 0, 0, -4, 0, 0, 0],
    [0, 0, 1, 2, 0, 3, 0, 0, 0],
    [0, 0, -2, 2, 2, -3, 0, 0, 0],
    [-1, -1, 1, 0, 0, -3, 0, 0, 0],
    [0, 1, 1, 0, 0, -3, 0, 0, 0],
    [0, -1, 1, 2, 2, -3, 0, 0, 0],
    [2, -1, -1, 2, 2, -3, 0, 0, 0],
    [0, 0, 3, 2, 2, -3, 0, 0, 0],
    [2, -1, 0, 2, 2, -3, 0, 0, 0]
  ];

  return tab.map((row) => {
    const o = {};
    PROPS.forEach((p, i) => {
      o[p] = row[i];
    });
    return o
  })
})();

var nutation$1 = {
  nutation,
  approxNutation,
  meanObliquity,
  meanObliquityLaskar,
  nutationInRA
};

exports.approxNutation = approxNutation;
exports["default"] = nutation$1;
exports.meanObliquity = meanObliquity;
exports.meanObliquityLaskar = meanObliquityLaskar;
exports.nutation = nutation;
exports.nutationInRA = nutationInRA;