f1=sym('t*(heaviside(t)-heaviside(t-1))');
f2=sym('(heaviside(t-1)-heaviside(t-2))');
f3=f1+f2;
figure;
subplot(311),ezplot(f3,[0,10]);
title('f(t)');
f4=subs(f3,t,t-4);
subplot(312),ezplot(f4,[0,10]);
title('f(t-4)');
f5 = subs(f3,t,4-2*t);
subplot(313),ezplot(f5,[0,10]);
set(gca,'Ylim',[0,1.2]);
title('f(-2t+4)');
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