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## Geodesic routines from GeographicLib

This documentation applies to version 1.49.

The documentation for other versions is available at https://geographiclib.sourceforge.io/m.nn/js for versions numbers m.nn ≥ 1.45.

Licensed under the MIT/X11 License; see LICENSE.txt.

### Installation

This library is a JavaScript implementation of the geodesic routines from GeographicLib. This solves the direct and inverse geodesic problems for an ellipsoid of revolution.

The library can be used in node by first installing the geographiclib node package with npm

``````\$ npm install geographiclib
\$ node
> var GeographicLib = require("geographiclib");``````

The npm package includes a test suite. Run this by

``````\$ cd node_modules/geograliblib
\$ npm test``````

Alternatively, you can use it in client-side JavaScript, by including in your HTML page

``````<script type="text/javascript"
src="https://geographiclib.sourceforge.io/scripts/geographiclib.js">
</script>``````

Both of these prescriptions define a GeographicLib namespace.

### Examples

Now geodesic calculations can be carried out, for example,

``````var geod = GeographicLib.Geodesic.WGS84, r;

// Find the distance from Wellington, NZ (41.32S, 174.81E) to
// Salamanca, Spain (40.96N, 5.50W)...
r = geod.Inverse(-41.32, 174.81, 40.96, -5.50);
console.log("The distance is " + r.s12.toFixed(3) + " m.");
// This prints "The distance is 19959679.267 m."

// Find the point 20000 km SW of Perth, Australia (32.06S, 115.74E)...
r = geod.Direct(-32.06, 115.74, 225, 20000e3);
console.log("The position is (" +
r.lat2.toFixed(8) + ", " + r.lon2.toFixed(8) + ").");
// This prints "The position is (32.11195529, -63.95925278)."``````

Two examples of this library in use are

### Change log

• Version 1.49 (released 2017-10-05)

• Use explicit test for nonzero real numbers.
• Version 1.48 (released 2017-04-09)

• Change default range for longitude and azimuth to (−180°, 180°] (instead of [−180°, 180°)).
• Version 1.47 (released 2017-02-15)

• Improve accuracy of area calculation (fixing a flaw introduced in version 1.46).
• Version 1.46 (released 2016-02-15)

• Fix bugs in PolygonArea.TestEdge (problem found by threepointone).
• Add Geodesic.DirectLine, Geodesic.ArcDirectLine, Geodesic.GenDirectLine, Geodesic.InverseLine, GeodesicLine.SetDistance, GeodesicLine.SetArc, GeodesicLine.GenSetDistance, GeodesicLine.s13, GeodesicLine.a13.
• More accurate inverse solution when longitude difference is close to 180°.

### Authors

• algorithms + js code: Charles Karney (charles@karney.com)
• node.js port: Yurij Mikhalevich (0@39.yt)