#!/usr/bin/python
# 5.1

import scipy as sp
from pylab import *

n = sp.arange(17)
subplot(2,2,1), stem(n,cos(n*pi/8))
grid,xlabel('n'),ylabel('cos(n*pi/8)')
subplot(2,2,2), stem(n,cos(n*pi/4))
grid,xlabel('n'),ylabel('cos(n*pi/4)')
subplot(2,2,3), stem(n,cos(n*pi/2))
grid,xlabel('n'),ylabel('cos(n*pi/2)')
subplot(2,2,4), stem(n,cos(n*pi))
grid,xlabel('n'),ylabel('cos(n*pi)')

show()