gistfile1.php

	public function getDistanceTo(Geometry_Point $anotherPoint)
	{
		//TODO!!!!
		if($this->getProjection() !== $anotherPoint->getProjection())
		{
			throw new Geometry_Exception('Projection mismatch');
		}


        $lat1 = $this->getLat();
        $lon1 = $this->getLng();

        $lat2 = $anotherPoint->getLat();
        $lon2 = $anotherPoint->getLng();

        $R = 6371000; //Radius of the Earth in meters
        $dLat = ($lat2-$lat1) * M_PI / 180;
        $dLon = ($lon2-$lon1) * M_PI / 180;
        $lat1 = $lat1 * M_PI / 180;
        $lat2 = $lat2 * M_PI / 180;

        $a = sin($dLat / 2) * sin($dLat / 2) +
            sin($dLon / 2) * sin($dLon / 2) * cos($lat1) * cos($lat2);
        $c = 2 * atan2(sqrt($a), sqrt(1-$a));
        $d = $R * $c;

        return $d;
	}