This routine calculates the distance between two points (given the latitude/longitude of those points). It is being used to calculate the distance between two locations:

function distance(point1, point2) { var EarthRadiusMeters = 6378137.0; var dLat = (point2[0] - point1[0]) * Math.PI / 180; var dLon = (point2[1] - point1[1]) * Math.PI / 180; var a = Math.sin(dLat / 2) * Math.sin(dLat / 2) + Math.cos(point1[0] * Math.PI / 180) * Math.cos(point2[0] * Math.PI / 180) * Math.sin(dLon / 2) * Math.sin(dLon / 2); var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a)); return EarthRadiusMeters * c; }

Example:

distance([32.9697, -96.80322],[29.46786, -98.53506])

Result:

`423232.8593012345`

Note: Result as meters

Ellipsoidal parameters:

Name Major axis, a (km) Flattening (f) WGS84 6378.13700 1/298.257223563 GRS80/NAD83 6378.13700 1/298.257222101 WGS66 6378.145 1/298.25 GRS67/IAU68 6378.16000 1/298.2472 WGS72 6378.135 1/298.26 Krasovsky 6378.245 1/298.3 Clarke66/NAD27 6378.2064 1/294.9786982138

Image copyright: movable-type.co.uk

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