#!/usr/bin/env python
 
# Haversine formula example in Python
# Author: Wayne Dyck
 
#import math
import numpy as np
 
def distance(origin, destination):
  lat1, lon1 = origin
  lat2, lon2 = destination
  radius = 6371 # km
 
  dlat = np.radians(lat2-lat1) #math.radians(lat2-lat1)
  dlon = np.radians(lon2-lon1) #math.radians(lon2-lon1)
  a = np.sin(dlat/2) * np.sin(dlat/2) + np.cos(np.radians(lat1))* np.cos(np.radians(lat2)) * np.sin(dlon/2) * np.sin(dlon/2)
  #a = math.sin(dlat/2) * math.sin(dlat/2) + math.cos(math.radians(lat1))* math.cos(math.radians(lat2)) * math.sin(dlon/2) * math.sin(dlon/2)
  c = 2 * np.arctan2(np.sqrt(a), np.sqrt(1-a)) #2 * math.atan2(math.sqrt(a), math.sqrt(1-a))
  d = radius * c
 
  return d