Geodesic Distance & Antimeridian-Safe Boxes

Haversine distance, initial bearing, and bounding-box containment, union and intersection that survive the antimeridian and the poles.

THE SILENT FAILURE. Naive code treats latitude and longitude as a plane. Euclidean distance on degrees is wrong everywhere and badly wrong away from the equator, because a degree of longitude shrinks toward the poles -- but it returns a plausible number, so nearest-location features ship subtly wrong for years. A bounding box crossing the ANTIMERIDIAN has minLon greater than maxLon, and naive containment returns FALSE for every point inside it, so a region near Fiji or the Aleutians silently contains nothing at all.

The mean Earth radius is cited to its source, and the accuracy limit versus an ellipsoidal model is stated rather than glossed -- overclaiming precision is the failure mode of every competing snippet. Distance is tested differentially against an independently written Vincenty implementation. Out-of-range latitude is REFUSED, never clamped, because clamping fabricates a location. Where a true intersection is two disjoint arcs and cannot be expressed as one box, it throws rather than silently discarding one.

An independent verifier found the shipped README quoted a bearing 8 degrees off the code's real output, and the test covering it asserted a range too wide to catch that. Both corrected; the assertion is now tight enough to fail.

VERIFIED: 89 tests. Every mutation was observed FAILING before the source was restored -- a test never seen to fail is a decoration. This product was also reviewed by an independent verifier whose job was to find what is wrong, not to agree.

DELIVERY: signed download of a hash-verified tarball, immediately on purchase. Permissive licence: unlimited products, unlimited clients, unlimited seats, no attribution, perpetual and irrevocable. One restriction, do not republish the source as source.

Interface

What you call, and what comes back. Types and signatures only — the implementation ships with the source.

  export function crossesAntimeridian(bbox: Bbox): boolean;
  export function bboxContainsPoint(bbox: Bbox, point: Point): boolean;
  export function bboxUnion(a: Bbox, b: Bbox): Bbox;
  export function bboxIntersection(a: Bbox, b: Bbox): Bbox | null;
  export function initialBearingDegrees(a: Point, b: Point): number;
  export function toRadians(degrees: number): number;
  export function haversineDistanceMeters(a: Point, b: Point, options: HaversineOptions = {}): number;
  export function isValidLatitude(lat: unknown): lat is number;
  export function isValidLongitude(lon: unknown): lon is number;
  export function assertValidPoint(p: Point): void;
  export function normalizeLongitude(lon: number): number;
  export function createPoint(lat: number, lon: number): Point;