anchor.diff:      111132.954 - 559.822 * math:cos(2.0 * LatRad) + 1.175 * math:cos(4.0 * LatRad).
   
   
  +% Returns the width of a longitudinal degree
  +% in meters for the given Latitude
  +longitudinal_width(Lat) ->
  +    LatRad = Lat * ?DEGREES_TO_RAD,
  +    Numerator = ?PI * ?RADIUS_METERS * math:cos(LatRad),
  +    Denom = 180 * math:sqrt(1 - ?E_SQ * math:pow(math:sin(LatRad), 2)),
  +    Numerator / Denom.
  +
  +
   -ifdef(TEST).
   
   distance_test() ->
  
positive.code: %%%
  -module(teles_geo_query).
  -export([query_within/2, query_around/3, query_nearest/3,
           distance/2, latitudinal_width/1]).
  -include_lib("rstar/include/rstar.hrl").
  
  -ifdef(TEST).
  
negative.code: 
  % Multiplier to convert degrees to radians
  -define(DEGREES_TO_RAD, 0.017453292519943295).
  
  % Constants
  -define(PI, 3.141592653589793).
  -define(E_SQ, 0.00669437999014).
  
  % Queries within a box, since the box is provided already, no adjustment
  % is necessary
  