Hi, I am trying (unsuccessfully) to migrate a formula (for calculating distances between lat/lng positions) from JavaScript to Ruby: //JavaScript: dlng = p2_lng - p1_lng dlat = p2_lat - p1_lat a = (sin(dlat/2))^2 + cos(p1_lat) * cos(p2_lat) * (sin(dlon/2))^2 c = 2 * atan2( sqrt(a), sqrt(1-a) ) distance = R * c (where R is the radius of the Earth) #Ruby: dlng = p2_lng - p1_lng dlat = p2_lat - p1_lat a = (Math.sin(dlat/2))**2 + Math.cos(p1_lat) * Math.cos(p2_lat) * (Math.sin(dlng/2))**2 c = 2 * Math.atan2( Math.sqrt(a), Math.sqrt(1-a) ) distance = 6373 * c #(radius of the Earth: 6373km Any idea why the Ruby one returns incorrect numbers? Ingo Weiss

on 2006-04-27 12:07

on 2006-04-27 12:23

is it possible that you need to make numbers explicitly float? eg: 2 --> 2.0