Python code for Simpson's rule

from math import *
def f(x):
  #function to integrate
  return sin(x)

def simpson_rule(a,b):
  #Approximation by Simpson's rule
  c=(a+b)/2.0
  h=abs(b-a)/2.0
  return h*(f(a)+4.0*f(c)+f(b))/3.0

# Calculates integral of f(x) from 0 to 1
print simpson_rule(0,1)

Integrating $\sin x$ from $0$ to $1$ with the previous code gives $0.45986218971...$ whereas the true value is $1-\cos 1 = 0.459697694131860282599063392557...$ .