S = load('q3data.csv'); % loads data from file to the workspace
f = S(:,1); % extract frequency
xr = S(:,2); %reference signal
x = S(:,3); % extract actual position
t = S(:,4); % extract time delay

for i=1:length(xr);
    freq(i) = 2*pi*f(i);
    period(i) = 1/f(i);
    g(i) = x(i)/xr(i);
    phase(i) = -360*t(i)/period(i);
end

zeta = 0.148;
wn = 27.391;
G = tf([wn*wn],[1 2*zeta*wn wn*wn]);

w = linspace(1,2*pi*50,10000);

[mag,shift]=bode(G,w);

figure(1);
subplot(2,1,1);
    loglog(freq,g,'Marker','o','LineStyle','none');
    hold on;
    %loglog(w,squeeze(mag));
title('Bode Plot'); ylabel('Log Gain [mm/mm]'); xlabel('Log Frequency[rad/sec]'); grid on;
subplot(2,1,2);
    semilogx(freq,phase,'Marker','o','LineStyle','none');
    hold on;
    %semilogx(w,squeeze(shift));
ylabel('Phase [deg]'); xlabel('Log Frequency[rad/sec]'); grid on;