OpenEuphoria

Re: Best way to...

• Posted by irv Oct 17, 2010
• 1745 views

Well, if you know how to phrase the question so it will fit on the subject line, please don't keep us in suspense.

Thanks for the suggestions. The following code, copied from a javascript version, works and gives a reasonably accurate distance, as well. This takes slightly more than 1 second on my computer, which is acceptable.

include std/math.e 
include std/sequence.e 
include std/get.e 
include std/io.e 
include std/sort.e 
 
constant R = 6371 -- km Radius of earth 
enum ID,LON,LAT,KM 
 
atom lat1, lat2, lon1, lon2, dLat, dLon, a, c, km, nm, sm 
 
-- current location (KLAX) 
lat1 = 33.9425346884195 
lon1 = -118.408074361323 
 
sequence airports = read_lines("index.txt") 
 
for i = 1 to length(airports) do 
 
	airports[i] &= "|0" -- place to store distance in km 
	airports[i] = split(airports[i],'|') 
	lat2 = defaulted_value(airports[i][LAT],0) 
	lon2 = defaulted_value(airports[i][LON],0) 
 
	dLat = deg2rad(lat2-lat1) 
	dLon = deg2rad(lon2-lon1)  
	a = sin(dLat/2) * sin(dLat/2) + 
		cos(deg2rad(lat1)) * cos(deg2rad(lat2)) *  
		sin(dLon/2) * sin(dLon/2) 
	c = 2 * atan2(sqrt(a), sqrt(1-a))  
	km = R * c 
	 
	--nm = km * 0.5399568034557235 
	--sm = km * 0.621371192237334 
	 
	airports[i][KM] = km 
 
	end for 
 
airports = sort_columns(airports,{KM}) 
 
for i =  1 to 3 do  
	printf(1,"%s %.2f km\n",{airports[i][ID],airports[i][KM]}) 
end for