function earth_distance in Location 7.5

Same name and namespace in other branches

1. 5.3 earth.inc \earth_distance()
2. 5 earth.inc \earth_distance()
3. 6.3 earth.inc \earth_distance()
4. 7.3 earth.inc \earth_distance()
5. 7.4 earth.inc \earth_distance()

1 call to earth_distance()

location_distance_between in ./location.inc

Given two points in lat/lon form, returns the distance between them.

File

./earth.inc, line 87

Trigonometry for calculating geographical distances. All function arguments and return values measure distances in metres and angles in degrees. The ellipsoid model is from the WGS-84 datum. Ka-Ping Yee, 2003-08-11

Code

function earth_distance($longitude1, $latitude1, $longitude2, $latitude2) {

  // Estimate the earth-surface distance between two locations.
  $long1 = deg2rad($longitude1);
  $lat1 = deg2rad($latitude1);
  $long2 = deg2rad($longitude2);
  $lat2 = deg2rad($latitude2);
  $radius = earth_radius(($latitude1 + $latitude2) / 2);
  $cosangle = cos($lat1) * cos($lat2) * (cos($long1) * cos($long2) + sin($long1) * sin($long2)) + sin($lat1) * sin($lat2);
  return acos($cosangle) * $radius;
}