clear
clf

ch5def = @(n, x) cos(n*acos(x));

N = 7
np = 100;
x = linspace(-1, 1, np);
tic();
y = ch5def(N, x);
ttt1 = toc();
plot(x, y)
hold on
tic();
z = ch5(N, x);
ttt2 = toc();
plot(x, z)
xlabel('x')
ylabel('T_n(x)')
title('Chebyshev polynomials')
legend('definition', 'recurrence', 'location', 'best')
grid on
ylim([-1, 1.5])

ttt1
ttt2