#!/usr/bin/env python
#
# taylor series for log(1+x)
#
import math

def exp(x):
  """Return exponetial of x."""

  x=float(x)

  if x<0.0:
    return 1.0/exp(-x)

  isum=1.0
  while x>1.0: 
    x-=1.0
    isum*=math.e

  sum=0.0
  term=1.0
  i=1
  while (sum + term) != sum:
    sum+=term
    term*=x/i
    i+=1
  return sum*isum


def log(x):
  """Return natural log of x."""

def sin(x):
  """Return sin(x)."""

def cos(x):
  """Return cos(x)."""

def tan(x):
  """Return tan(x)."""