Distance between two coordinates in php using haversine

Question

I've looked around and seen mention of the haversine formula to determine distance between two coordinates (lat1, lng1) and (lat2, lng2).

I've implemented this code:

    function haversineGreatCircleDistance(
  $latitudeFrom, $longitudeFrom, $latitudeTo, $longitudeTo, $earthRadius = 6371000)
{
  // convert from degrees to radians
  $latFrom = deg2rad($latitudeFrom);
  $lonFrom = deg2rad($longitudeFrom);
  $latTo = deg2rad($latitudeTo);
  $lonTo = deg2rad($longitudeTo);

  $latDelta = $latTo - $latFrom;
  $lonDelta = $lonTo - $lonFrom;

  $angle = 2 * asin(sqrt(pow(sin($latDelta / 2), 2) +
    cos($latFrom) * cos($latTo) * pow(sin($lonDelta / 2), 2)));
  return $angle * $earthRadius;
}

And am trying to determine:

1) what units this is returning? (goal being in feet)

2) is this equation written the right way?

For example what should be the distance between these two points?

(32.8940695525,-96.7926336453) and (33.0642604502, -96.8064332754)?

I'm getting 18968.0903312 from the formula above.

Thanks!

Matt Ball Matt Ball · Accepted Answer · 2013-02-28T16:28:30

1) what units this is returning? (goal being in feet)

Whatever units in which you supply the Earth's radius.

2) is this equation written the right way?

Test it. You can compare your results with an existing Haversine formula implementation, like this one.

Distance between two coordinates in php using haversine

1 Answers