haversine formula php / mysql - php

Question

I'm trying to get a common database of geo points working with a radius search.
I've found several good tutorials on this topic, but I'm failing at the very end.
The main tutorial is here: http://janmatuschek.de/LatitudeLongitudeBoundingCoordinates.
The basic formula, in the form of an SQL query, is
SELECT * FROM Places
WHERE (Lat => 1.2393 AND Lat <= 1.5532) AND (Lon >= -1.8184 AND Lon <= 0.4221)
AND acos(sin(1.3963) * sin(Lat) + cos(1.3963) * cos(Lat) * cos(Lon - (-0.6981)))
<= 0.1570;
I've implemented this in a simple PHP test page like this:
$R = 6371; // radius of Earth in KM
$lat = '46.98025235521883'; // lat of center point
$lon = '-110.390625'; // longitude of center point
$distance = 1000; // radius in KM of the circle drawn
$rad = $distance / $R; // angular radius for query
$query = '';
// rough cut to exclude results that aren't close
$max_lat = $lat + rad2deg($rad/$R);
$min_lat = $lat - rad2deg($rad/$R);
$max_lon = $lon + rad2deg($rad/$R/cos(deg2rad($lat)));
$min_lon = $lon - rad2deg($rad/$R/cos(deg2rad($lat)));
// this part works just fine!
$query .= '(latitude > ' . $min_lat . ' AND latitude < ' . $max_lat . ')';
$query .= ' AND (longitude > ' . $min_lon . ' AND longitude < ' . $max_lon . ')';
// refining query -- this part returns no results
$query .= ' AND acos(sin('.$lat.') * sin(latitude) + cos('.$lat.') * cos(latitude) *
cos(longitude - ('.$lon.'))) <= '.$rad;
Am I missing something here? I think I'm following the methodology exactly, but I cannot get the "fine tuning" query to return any results.

Answer 1

not sure but :
$R = 6371; // radius of Earth in KM
$lat = '46.98025235521883'; // lat of center point
$lon = '-110.390625'; // longitude of center point
$distance = 1000; // radius in KM of the circle drawn
$rad = $distance / $R; // angular radius for query
$query = '';
// rough cut to exclude results that aren't close
$radR = rad2deg($rad/$R);
$max_lat = $lat + radR;
$min_lat = $lat - radR;
$radR = rad2deg($rad/$R/cos(deg2rad($lat)));
$max_lon = $lon + radR;
$min_lon = $lon - radR;
// this part works just fine!
$query .= '(latitude > ' . $min_lat . ' AND latitude < ' . $max_lat . ')';
$query .= ' AND (longitude > ' . $min_lon . ' AND longitude < ' . $max_lon . ')';
// refining query -- this part returns no results
$query .= ' AND acos(sin('.deg2rad($lat).') * sin(radians(latitude)) + cos('.deg2rad($lat).') * cos(radians(latitude)) *
cos(radians(longitude) - ('.deg2rad($lon).'))) <= '.$rad;