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Add JDN to Gregorian date converter

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Quantum 2022-02-12 13:17:24 -05:00
parent 087f4015f7
commit 0c039a04c4
2 changed files with 37 additions and 1 deletions
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23
src/dates.test.ts
View file

@ -1,4 +1,4 @@
import {dateName, frJDN, gregorianJDN, monthName} from './dates';
import {dateName, frJDN, gregorianJDN, jdnGregorian, monthName} from './dates';
describe('gregorianJDN', () => {
it('works', () => {
@ -30,6 +30,27 @@ describe('frJDN', () => {
});
});
describe('jdnGregorian', () => {
it('works', () => {
expect(jdnGregorian(0)).toEqual(new Date(-4713, 11, 24));
expect(jdnGregorian(2299160)).toEqual(new Date(1582, 10, 14));
expect(jdnGregorian(2299161)).toEqual(new Date(1582, 10, 15));
expect(jdnGregorian(2361221)).toEqual(new Date(1752, 9, 13));
expect(jdnGregorian(2361222)).toEqual(new Date(1752, 9, 14));
expect(jdnGregorian(2451545)).toEqual(new Date(2000, 1, 1));
expect(jdnGregorian(-8512316)).toEqual(new Date(-28019, 12, 20));
expect(jdnGregorian(-8534852)).toEqual(new Date(-28080, 4, 8));
expect(jdnGregorian(2653462)).toEqual(new Date(2552, 10, 30));
expect(jdnGregorian(3271156)).toEqual(new Date(4244, 1, 8));
expect(jdnGregorian(-666477)).toEqual(new Date(-6537, 2, 23));
expect(jdnGregorian(2397854)).toEqual(new Date(1852, 12, 31));
expect(jdnGregorian(-1211235)).toEqual(new Date(-8029, 8, 26));
expect(jdnGregorian(-91680)).toEqual(new Date(-4964, 11, 20));
expect(jdnGregorian(-5605876)).toEqual(new Date(-20061, 7, 14));
expect(jdnGregorian(-295121)).toEqual(new Date(-5521, 11, 19));
});
});
describe('monthName', () => {
it('works', () => {
expect(monthName(1)).toBe('Vendémiaire');

15
src/dates.ts
View file

@ -34,6 +34,12 @@ export type Day =
| 29
| 30;
export type GregorianDate = {
year: number,
month: number,
day: number,
};
const monthNames: {
[key in Month]: string
} = {
@ -81,6 +87,15 @@ export function frJDN(year: number, month: Month, day: Day): number {
return startJD + 365 * dy + leaps[dy] + dd;
}
export function jdnGregorian(jdn: number): Date {
const e = 4 * (jdn + 1401 + Math.floor(Math.floor((4 * jdn + 274277) / 146097) * 3 / 4) - 38) + 3;
const h = 5 * Math.floor((e % 1461 + 1461) % 1461 / 4) + 2;
const day = Math.floor((h % 153 + 153) % 153 / 5) + 1;
const month = (Math.floor(h / 153) + 2) % 12 + 1;
const year = Math.floor(e / 1461) - 4716 + Math.floor((14 - month) / 12);
return new Date(year, month, day);
}
export function monthName(month: Month): string {
return monthNames[month];
}