Function f with varying values of a Plot

t = 0 : 0.001 : pi / 2; % Create a vector of a lot of values between 0 and pi / 2
% So that time appears continuous when we plot graphs
figure
hold on
a = 1;
f = a * sin(t);
plot(t, f);
a = 2;
f = a * sin(t);
plot(t, f);
a = 1/2;
f = a * sin(t);
plot(t, f);
xlabel('Time');
ylabel('Function f(t)')
title('Function f with varying values of a')
legend('a = 1', 'a = 2', 'a = 0.5')
hold off