Haversine distance formula calculator for PHP, with some little hacks and a lot of parameters.

php_haversine_example

/**
     * Haversine distance formula.
     *
     * This calculates the distance between geo coordinates in km<br>
     * Algorithm: http://www.scribd.com/doc/2569355/Geo-Distance-Search-with-MySQL<br>
     * Full calculation with Haversine formula is slow, so limit the whole distance to a rectangle,
     * then calculate the distance.
     * <br>
     * 1° of lat -> 111km (69 miles)<br>
     * 1° of lon -> cos(lat)*111<br>
     * <br>
     * The "countit" version is a dirty hack, but it works....<br><br>
     * <br>
     * IMPORTANT: Be very careful with the parameters and NEVER use unfiltered user input!
     * <br><br>
     * @param   exp         Expression, what you want to give back (SELECT <exp>, distance FROM...)
     * @param   table       Database for the calculation (user, question, etc..)
     * @param   lat         Latitude
     * @param   lon         Longtitude
     * @param   radius      Radius in meter
     * @param   limit       SQL limit         (DEFAULT: 1000)
     * @param   limitMax    SQL limit maximum
     * @param   wheres      Possible more WHERE conditions
     * @param   latname     Name of the lat fieald
     * @param   lonname     Name of the lon fieald
     * @param   areaname    Name of the area fieald
     * @param   countit     Only count the result or not
     * @param   countit_distinct Limitations for the count
     * @param   groupby     Group by param
     * 
     * @return  An array with the 'exp' or all the values and a 'distance' key value
     * <br>
     * <br>
     * Example: haversineCalculator(array('table' => 'user', 'lat' => 19.01213, 'lon' => 21.00232, 'radius' => 400));<br>
     * This'll give back the results from the 'user' table (where you need to have a lat, lon and area column).
     */
    function haversineCalculator($params = array()){
        $defaults = array(
            'exp' => '*',
            'table' => '',
            'lat' => 0,
            'lon' => 0,
            'radius' => 5000, //you should put this in a config file for example
            'limit' => 1000,
            'limitMax' => '',
            'order' => 'distance',
            'wheres' => '',
            'latname' => 'lat',
            'lonname' => 'lon',
            'areaname' => 'area',
            'countit' => false,
            'countit_distinct' => '*',
            'groupby' => ''
            );
        $params = array_merge($defaults, $params);

        //Not too beautiful, but I don't want to touch the code below
        $exp = $params['exp'];
        $db = $params['table'];
        $lat = $params['lat'];
        $lon = $params['lon'];
        $dist = ($params['radius'] + 5000) / 1000; //km -> m conversion, the database calculates with km + the '5000' value should come from the max distance config file or somewhere
        //get a bigger area for circle engraving
        $latname = $params['latname'];
        $lonname = $params['lonname'];
        $radiusname = $params['areaname'];
        
        $wheres = $params['wheres'];
        

        //calcluate a rectangular area first
        $lon1 = $lon - ($dist / abs( cos(deg2rad($lat))*111.0447 ));
        $lon2 = $lon + ($dist / abs( cos(deg2rad($lat))*111.0447 ));
        $lat1 = $lat - ($dist / 111.0447);
        $lat2 = $lat + ($dist / 111.0447);
        //echo "DST: ".$dist."km, " .$lon1." ".$lon2." - ".$lat1." ".$lat2."<br />";


        if($params['countit']){
            //changed the count stuff
            $res = R::getAll('SELECT count('.$params['countit_distinct'].') as number from (SELECT '.$exp.',
            ( 6371 * 2 *
                ASIN(SQRT( POWER(SIN(( :lat -  ('.$db.'.'.$latname.')) * pi()/180 / 2), 2)
               +COS( :lat *pi()/180) * COS( ('.$db.'.'.$latname.')*pi()/180)*
               POWER(SIN( ( :lon - '.$db.'.'.$lonname.') * pi()/180 / 2 ),2 )
                ))  ) AS distance
            FROM '.$db.' WHERE '.$lonname.' BETWEEN '.$lon1.' and '.$lon2.' AND '.$latname.' BETWEEN '.$lat1.' and '.$lat2.' '.$wheres.' 
            '. ( !empty($params['groupby'])? 'GROUP BY '.$params['groupby']:'' ) .'
            HAVING distance < ( :area + ('.$db.'.'.$radiusname.'/1000) ) ORDER BY '.$params['order'].' LIMIT :limit '.$params['limitMax'].') as t;',
            array(':lat' => $lat,
                  ':lon' => $lon,
                  ':area' => ($params['radius']/1000),
                  /*':order' => $params['order'],*/
                  ':limit' => $params['limit'],
                 ));


        }else{
            $res = R::getAll('SELECT '.$exp.',
            ( 6371 * 2 *
                ASIN(SQRT( POWER(SIN(( :lat -  ('.$db.'.'.$latname.')) * pi()/180 / 2), 2)
               +COS( :lat *pi()/180) * COS( ('.$db.'.'.$latname.')*pi()/180)*
               POWER(SIN( ( :lon - '.$db.'.'.$lonname.') * pi()/180 / 2 ),2 )
                ))  ) AS distance
            FROM '.$db.' WHERE '.$lonname.' BETWEEN '.$lon1.' and '.$lon2.' AND '.$latname.' BETWEEN '.$lat1.' and '.$lat2.' '.$wheres.' 
            '. ( !empty($params['groupby'])? 'GROUP BY '.$params['groupby']:'' ) .'
            HAVING distance < ( :area + ('.$db.'.'.$radiusname.'/1000) ) ORDER BY '.$params['order'].' LIMIT :limit '.$params['limitMax'],
            array(':lat' => $lat,
                  ':lon' => $lon,
                  ':area' => ($params['radius']/1000),
                  /*':order' => $params['order'],*/
                  ':limit' => $params['limit'],
                 ));
        }
        

        //Maybe try this
        //https://developers.google.com/maps/articles/phpsqlsearch_v3
        
        return $res;
    }