clear all;
clf;

fs = 3;
Ts = 1/fs;
num_sec = 6;
ws = 2*pi*fs;
wc = ws/2;
t = linspace(-floor(num_sec/2), floor(num_sec/2), num_sec*100+1);

x = exp(-2*t.^2).*cos((2*pi).*t);
h = Ts*wc/pi*sinc(wc.*t/pi);
xp = zeros(1, num_sec*fs);
tp = zeros(1, num_sec*fs);

index = 1;
dec = 0;
for iter = 1:length(t)
    if(t(iter) < 0)
        dec = t(iter) - ceil(t(iter));
    else
        dec = t(iter) - floor(t(iter));
    end
    for k = -floor(num_sec/2):floor(num_sec/2)
        if(round(dec, 2) == round(k*Ts, 2))
            for n = 1:fs
                xp(index) = x(iter);
                tp(index) = t(iter);
                index = index + 1;
            end
        end
    end
end

xr = zeros(1, length(xp));

for iter = 1:length(tp)
    for n2 = -10000:10000
        xr(iter) = xr(iter) + xp(iter)*Ts*wc/pi*...
            sinc(wc*(t(iter)-n2*Ts)/pi);
    end
end

figure(1);
plot(t, x, 'b'); hold on
plot(tp, xr, 'r')
plot(tp, xp, 'or');

xlabel('time (s)');
axis([-floor(num_sec/2) floor(num_sec/2) -1.2 1.2]);