import math
a=[1,2,3,4]
b=a   
for k in range(4):
    b[k] = math.cos(a[k])
from pylab import * 
from math import sin
from numpy import *
xlabel('x')
ylabel('y')
title('exemple de plot') 
grid(True)
t = arange(0.0,3.0,0.01)  
s=sin(2*pi*t)
plot(t,s)