% Plot sine wave
pi=3.1415;
t1 = 0:0.01:2;
t2 = 0:0.01:4;
w=2*pi;
wt1 = w*t1;
wt2 = w*t2;
x1 = 2*sin(w*t1);
x2 = 2*sin(w*t2);
subplot(211); 
plot(wt1, x1, 'linewidth',2); grid; xlabel('wt'); ylabel('x(t)');

subplot(212); 
plot(wt2/2, x2, 'linewidth',2); grid; xlabel('wt'); ylabel('x(2t)')
figure(1);