MySQL Helper class for calculating Distances between to geo locations

GeoLocator

<?php

class GeoLocator
{

        /**
         * @var string
         */
        public static $tableGeoPostcodeSuburbState = 'geoAustralianLocations';

        const EARTH_RADIUS_KM   = 6378.137;
        const EARTH_RADIUS_MILE = 3963.191;

        const KM_PER_LATITUDE   = 111.325;      // we use this value if we are dealing with degrees than radians


        /**
         * Get the Geo Proximity equation
         * 
         * We are using the WGS 84 reference coordinate system which incidently is
         * used by the Global Positioning System
         * 
         * @param integer $locationLatitude
         * @param integer $locationLongitude
         * @param string $tableAlias
         * @return string 
         */
        public static function getProximityEquation( $locationLatitude, $locationLongitude, $tableAlias )
        {
                return "
                ROUND(
                        (
                                " . GeoLocator::EARTH_RADIUS_KM . " * 
                                ACOS(
                                        (
                                                SIN(PI() * {$locationLatitude} / 180) * 
                                                SIN(PI() * {$tableAlias}.geoLatitude / 180)
                                        ) + 
                                        (
                                                COS(PI() * {$locationLatitude} /180) * 
                                                COS(PI() * {$tableAlias}.geoLatitude / 180) * 
                                                COS(PI() * {$tableAlias}.geoLongitude / 180 - PI() * {$locationLongitude} / 180)
                                        ) 
                                )
                        ),
                        2
                )
                ";
        }

        /**
         * Calculate the distance between latitude and longitude coordinates
         *
         * @param string $fromLatitude
         * @param string $fromLongitude
         * @param string $toLatitude
         * @param string $toLongitude
         * @return integer value in Kms
        */
        public static function calculateDistanceProximity($fromLatitude, $fromLongitude, $toLatitude, $toLongitude)
        {
                return
                round(
                        (
                                acos
                                (
                                        (
                                                sin(deg2rad($fromLatitude)) *
                                                sin(deg2rad($toLatitude))
                                        ) +
                                        (
                                                cos(deg2rad($fromLatitude)) *
                                                cos(deg2rad($toLatitude)) *
                                                cos(deg2rad($fromLongitude - $toLongitude))
                                        )
                                ) *
                                GeoLocator::EARTH_RADIUS_KM
                        ),
                        2
                );

        }



}

?>