#!/usr/bin/env python

#-------------
# Load modules
#-------------

import sys
import math

#------------------------------
# Count the number of arguments
#------------------------------

n = len(sys.argv[1:])
if (n > 0):
   print "You want to compute the natural logarithm of %d values" %(n)
else:
   print """
   Usage:  
       ./naturalLog.py val1 val2 val3 ...
   """
   sys.exit(1)

#--------------------------------------------
# Define the function printing the logarithms
#--------------------------------------------

def printLog(r):
    if r > 0:
       s = math.log(r)
       print " ln(%g) = %e" %(r,s)
    else:
       print " ln(%g) is illegal" %(r)

#---------------------------------
# Directly loop over the arguments
#---------------------------------

#for v in sys.argv[1:]:
#    r = float(v)
#    printLog(r)

#--------------------------------------
# for loop with the number of arguments
#--------------------------------------

#for i in range(1,n+1):
#    r = float(sys.argv[i])
#    printLog(r)

#----------------------------------------
# while loop with the number of arguments
#----------------------------------------

#i = 1
#while i <= n:
#    r = float(sys.argv[i])
#    printLog(r)
#    i += 1

#--------------------
# Infinite while loop (no assumption on the number of arguments)
#--------------------

#i = 1
#while 1:
#    try:
#       r = float(sys.argv[i])
#       printLog(r)
#       i += 1
#    except:
#       sys.exit(1)