Terrestrial is a zero-trigonometry WGS84 ellipsoidal geodesic distance engine that projects reduced latitudes and longitudinal chords through algebraic Horner polynomials, Alexandrian apothem-sagitta rectification, and bitwise antimeridian wrapping, returning target locations sorted from nearest to farthest.
Deno:
deno add npm:@neabyte/terrestrialnpm:
npm install @neabyte/terrestrialCDN (jsDelivr/esm.sh):
<script type="module">
import Terrestrial from 'https://cdn.jsdelivr.net/npm/@neabyte/terrestrial/dist/index.mjs'
</script>Or via esm.sh:
<script type="module">
import Terrestrial from 'https://esm.sh/@neabyte/terrestrial'
</script>import Terrestrial from '@neabyte/terrestrial'
// Nearest targets come back first
const result = Terrestrial.calculate({
origin: {
name: 'Jakarta',
latitude: -6.2088,
longitude: 106.8456
},
targets: [
{
name: 'Tokyo',
latitude: 35.6762,
longitude: 139.6503
},
{
name: 'Bandung',
latitude: -6.9175,
longitude: 107.6191
},
{
name: 'Singapore',
latitude: 1.3521,
longitude: 103.8198
}
],
unit: 'km'
})
console.log(result)
// [
// {
// name: 'Bandung',
// latitude: -6.9175,
// longitude: 107.6191,
// distance: 116.01894...
// },
// {
// name: 'Singapore',
// latitude: 1.3521,
// longitude: 103.8198,
// distance: 901.16526...
// },
// {
// name: 'Tokyo',
// latitude: 35.6762,
// longitude: 139.6503,
// distance: 5767.69086...
// }
// ]targets with an empty array returns [], and invalid coordinates or units throw a TypeError or RangeError.
| Parameter | Type | Description |
|---|---|---|
params.origin |
TerrestrialLocation |
Origin location (name, latitude in [-90, 90], longitude in [-180, 180]). |
params.targets |
TerrestrialLocation[] |
Target locations to measure against origin. |
params.unit |
'km' | 'm' | 'mi' |
Output distance unit (kilometers, meters, or miles). |
Returns: TerrestrialResult[], sorted by ascending distance (nearest first).
interface TerrestrialLocation {
latitude: number
longitude: number
name: string
}
interface TerrestrialParams {
targets: TerrestrialLocation[]
origin: TerrestrialLocation
unit: 'km' | 'm' | 'mi'
}
interface TerrestrialProject {
cosine: number
sine: number
}
interface TerrestrialResult extends TerrestrialLocation {
distance: number
}| Property | Value | Description |
|---|---|---|
Terrestrial.equator |
6378137.0 |
WGS84 equatorial radius in meters. |
Terrestrial.flattening |
1 / 298.257223563 |
WGS84 ellipsoidal flattening ratio. |
Distances from Null Island (0°, 0°) to 249 ISO 3166-1 locations, measured in meters and compared with Vincenty on the WGS84 ellipsoid.
| Metric | Error |
|---|---|
| Median | 1.001 m |
| Mean | 11.267 m |
| 95th percentile | 72.019 m |
| Maximum | +357.838 m (Tokelau, 19.177 ppm) |
Short and mid-range routes stay near a meter, while the larger gaps show up on antipodal Pacific routes of about 17,000 to 19,000 km. The full country table is in ACCURACY.md.
npm run builddeno task checkdeno task testThis repository is licensed under Apache 2.0.