##Longitude and Latitude things.
##Harry Decamp
##8/10/2011
import math

def DistanceCalculator(long1, lat1, long2, lat2):
    lat1 = math.radians(lat1)
    lat2 = math.radians(lat2)
    long1 = math.radians(long1)
    long2 = math.radians(long2)
    if abs(long1) > abs(long2):
        difflong = abs(long1) - abs(long2)
    else:
        difflong = abs(long2) - abs(long1)

    if abs(lat1) > abs(lat2):
        difflat = abs(lat1) - abs(lat2)
    else:
        difflat = abs(lat2) - abs(lat1)

    #Haversine Formula for working out the distance between 2 points
    first = math.sin(difflat / 2) ** 2 + math.cos(lat1) * math.cos(lat2) * math.sin(difflong / 2) ** 2
    second = 2 * math.atan2(math.sqrt(first), math.sqrt(1 - first))
    radiusw = 6378
    distance = radiusw * second
    print "Aproximatly " + str(distance) + " Kilometers."




print "---------------------"
long1 = input("Current Longitude: ")
lat1 = input("Current Latitude: ")
print "---------------------"
long2 = input("Destination Longitude: ")
lat2 = input("Destination Latitude: ")
print "---------------------"


DistanceCalculator(long1, lat1, long2, lat2)