import { Coordinates } from "../airports/types.js";

//#region source/helpers/geodesy.d.ts
/**
 * Returns the distance along the surface of the earth between two points.
 *
 * Uses haversine formula:
 * a = sin²(Δφ/2) + cos φ1 ⋅ cos φ2 ⋅ sin²(Δλ/2);
 * c = 2 ⋅ atan2(√a, √(1−a));
 * d = R ⋅ c;
 *
 * where φ is latitude, λ is longitude, R is earth’s radius (mean radius = 6,371km);
 * note that angles need to be in radians to pass to trig functions!
 *
 * note greek letters (e.g. φ, λ, θ) are used for angles in radians to distinguish from angles in
 * degrees (e.g. lat, lon, brng)
 *
 * @param start - Latitude/longitude of start point.
 * @param end - Latitude/longitude of destination point.
 * @param radius - Radius of earth (defaults to mean radius in metres).
 * @returns Distance between two points, in meters.
 *
 * @example
 */
declare const distance: (start: Coordinates, end: Coordinates, radius?: number) => number;
//#endregion
export { distance };