Signals and Systems - Electrical Engineering

48 C H A P T E R 0: From the Ground Up!

− 1 0 1

−0.5

0

0.5

1

x

y

x=cos(2πt), y=cos(2πt) x=cos(2πt), y=cos(4πt)

x=cos(2πt), y=cos(6πt) x=cos(2πt), y=cos(8πt)

− 1 0 1

−0.5

0

0.5

1

x

y

− 1 0 1

−0.5

0

0.5

1

x

y

− 1 0 1

−0.5

0

0.5

1

x

(a) (b)

(c) (d)

y

FIGURE 0.23

The Chebyshev polynomials forn=1, 2, 3, 4. First (a) to fourth (d) polynomials. Notice that these polynomials

are defined between[−1, 1]in thexaxis.

clear all;clf

syms x y t

x = cos(2∗pi∗t); theta=0;

figure(1)

for k = 1:4,

y = cos(2∗pi∗k∗t + theta);

if k == 1, subplot(221)

elseif k == 2, subplot(222)

elseif k == 3, subplot(223)

else subplot(224)

end

ezplot(x, y);grid;hold on

end

hold off