neaps/packages/tide-predictor/test/astronomy/index.test.ts at 164759fc8c76e32dd3fb16bea2af4feab6a7da2d · openwatersio/neaps · GitHub

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import { describe, it, expect } from "vitest";
import astro, {
  polynomial,
  derivativePolynomial,
  JD,
  T,
  _I,
  _xi,
  _nu,
  _nup,
  _nupp,
} from "../../src/astronomy/index.js";

const sampleTime = new Date("2019-10-04T10:15:40.010Z");

describe("astronomy", () => {
  it("complete astronomic calculation", () => {
    const result = astro(sampleTime);
    expect(result.s.value).toBeCloseTo(258.23871057233191, 4);
    expect(result.s.speed).toBeCloseTo(0.54901651929993922, 4);

    expect(result.pp.value).toBeCloseTo(283.27697979858613, 4);
    expect(result.pp.speed).toBeCloseTo(1.9612154426341654e-6, 4);

    expect(result.h.value).toBeCloseTo(192.82639897760328, 4);
    expect(result.h.speed).toBeCloseTo(0.041068640143510367, 4);

    expect(result.xi.value).toBeCloseTo(11.989946298635664, 4);
    expect(result.xi.speed).toBeNull();

    expect(result.I.value).toBeCloseTo(22.811296275568843, 4);
    expect(result.I.speed).toBeNull();

    expect(result.P.value).toBeCloseTo(155.24265065565865, 4);
    expect(result.P.speed).toBeNull();

    expect(result.nupp.value).toBeCloseTo(8.8162480626605451, 4);
    expect(result.nupp.speed).toBeNull();

    expect(result.nu.value).toBeCloseTo(13.028571777192044, 4);
    expect(result.nu.speed).toBeNull();

    expect(result["T+h-s"].value).toBeCloseTo(88.50435506200392, 4);
    expect(result["T+h-s"].speed).toBeCloseTo(14.492052120843571, 4);

    expect(result.omega.value).toBeCloseTo(23.436722306067253, 4);
    expect(result.omega.speed).toBeCloseTo(-1.4832917321024327e-8, 4);
  });

  it("evaluates a polynomial", () => {
    expect(polynomial([1, 2, 3], 3)).toBe(34);
  });

  it("evaluates derivative polynomials", () => {
    expect(derivativePolynomial([1, 2, 3], 3)).toBe(20);
  });

  it("evaluates Meeus formula 7.1 (JD) correctly", () => {
    const time = new Date(sampleTime);
    time.setUTCMonth(9);
    expect(JD(time)).toBeCloseTo(2458760.92755, 2);
    // Months of less than 2 go back a year
    time.setUTCMonth(0);
    expect(JD(time)).toBeCloseTo(2458487.92755, 2);
  });

  it("evaluates Meeus formula 11.1 (T) correctly", () => {
    sampleTime.setMonth(9);
    expect(T(sampleTime)).toBeCloseTo(0.19756132, 2);
  });

  it("evaluates value for _I correctly", () => {
    expect(_I(4, 10, 5)).toBeCloseTo(14.9918364991, 4);
  });

  it("evaluates value for _xi correctly", () => {
    expect(_xi(4, 3, 10)).toBeCloseTo(0.911946348144, 4);
  });

  it("evaluates value for _nu correctly", () => {
    expect(_nu(10, 4, 5)).toBeCloseTo(4.45767377718, 4);
  });

  it("evaluates value for _nup correctly", () => {
    expect(_nup(10, 4, 5)).toBeCloseTo(2.13580480226, 4);
  });

  it("evaluates value for _nupp correctly", () => {
    expect(_nupp(10, 4, 5)).toBeCloseTo(1.1146589591, 4);
  });
});