function earth_longitude_range in Location 7.3

Same name and namespace in other branches

1. 5.3 earth.inc \earth_longitude_range()
2. 5 earth.inc \earth_longitude_range()
3. 6.3 earth.inc \earth_longitude_range()
4. 7.5 earth.inc \earth_longitude_range()
5. 7.4 earth.inc \earth_longitude_range()

Earth longitude range.

@todo This function uses earth_asin_safe so is not accurate for all possible parameter combinations. This means this function doesn't work properly for high distance values. This function needs to be re-written to work properly for larger distance values.

See also

http://drupal.org/node/821628

3 calls to earth_longitude_range()

location_handler_argument_location_proximity::query in handlers/location_handler_argument_location_proximity.inc

Set up the query for this argument.

location_search_search_execute in contrib/location_search/location_search.module

Implements hook_search_execute().

location_views_handler_filter_proximity::query in handlers/location_views_handler_filter_proximity.inc

Add this filter to the query.

File

./earth.inc, line 169

Trigonometry for calculating geographical distances. All function arguments and return values measure distances in metres and angles in degrees. The ellipsoid model is from the WGS-84 datum. Ka-Ping Yee, 2003-08-11

Code

function earth_longitude_range($longitude, $latitude, $distance) {

  // Estimate the min and max longitudes within $distance of a given location.
  $long = deg2rad($longitude);
  $lat = deg2rad($latitude);
  $radius = earth_radius($latitude) * cos($lat);
  if ($radius > 0) {
    $angle = abs($distance / $radius);
    $angle = min($angle, pi());
  }
  else {
    $angle = pi();
  }
  $minlong = $long - $angle;
  $maxlong = $long + $angle;
  if ($minlong < -pi()) {
    $minlong = $minlong + pi() * 2;
  }
  if ($maxlong > pi()) {
    $maxlong = $maxlong - pi() * 2;
  }
  return array(
    rad2deg($minlong),
    rad2deg($maxlong),
  );
}