#https://gist.github.com/thinkphp/1528363 
 
  1 + 1/1! + 1/2! + 1/3! + ... 
  2 + 1/2! + 1/3!+ ... 
'''  
import math  
  
def fact(n):  
    if n == 0:  
       return 1  
    else:  
       return n*fact(n-1)  
  
def e(EPS):  
  
    v1 = 2  
    v2 = v1 + float(1.0/fact(2))  
    i = 3   
    while math.fabs(v1-v2) >= EPS:  
          v1 = v2  
          v2 += float(1.0/fact(i))  
          i += 1  
    return v2    
  
print("The mathematical constant e")  
#computes the value of e using infinite series  
print(e(0.00000001))  
#mathematical constant e build-in  
print(math.e)