Plotting multi-component signals

I'm trying to plot a multi-component signal composed of the following segments in the following order:

    epoch1 = 0.5*cos(pi*t) + 1.5*cos(4*pi*t) + 4*cos(5*pi*t);
    epoch2 = 0.7*cos(pi*t) + 2.1*cos(4*pi*t) + 5.6*cos(5*pi*t);
    epoch3 = 1.5*cos(2*pi*t) + 4*cos(8*pi*t);
    epoch4 = 1.5*cos(pi*t) + 4*cos(4*pi*t);
    epoch5 = 0.5*cos(pi*t) + 1.7*cos(2*pi*t) + 3.7*cos(5*pi*t);
    epoch6 = 2.3*cos(3*pi*t) + 7.8*cos(8*pi*t);
    epoch7 = 0.8*cos(pi*t) + cos(3*pi*t) + 3*cos(5*pi*t);

It should look like this:

I tried this:

    t = [0:0.0001:50];

    epoch1 = 0.5*cos(pi*t) + 1.5*cos(4*pi*t) + 4*cos(5*pi*t);
    epoch2 = 0.7*cos(pi*t) + 2.1*cos(4*pi*t) + 5.6*cos(5*pi*t);
    epoch3 = 1.5*cos(2*pi*t) + 4*cos(8*pi*t);
    epoch4 = 1.5*cos(pi*t) + 4*cos(4*pi*t);
    epoch5 = 0.5*cos(pi*t) + 1.7*cos(2*pi*t) + 3.7*cos(5*pi*t);
    epoch6 = 2.3*cos(3*pi*t) + 7.8*cos(8*pi*t);
    epoch7 = 0.8*cos(pi*t) + cos(3*pi*t) + 3*cos(5*pi*t);

    figure;
    hold
    plot(t, epoch1);
    plot(t, epoch2);
    plot(t, epoch3);
    plot(t, epoch4);
    plot(t, epoch5);
    plot(t, epoch6);
    plot(t, epoch7);

The paper I'm reading says that it's using 50 synthetic multi-component data, which makes me think that it is sampling data points from these functions and then plotting the data points, but I'm not sure how to do that. Any help on how to to do this is appreciated.

Answer 1

[Romil Shah]

    t = [1:0.1:7];
    epoch1 = 0.5*cos(pi*t) + 1.5*cos(4*pi*t) + 4*cos(5*pi*t);
    epoch2 = 0.7*cos(pi*t) + 2.1*cos(4*pi*t) + 5.6*cos(5*pi*t);
    epoch3 = 1.5*cos(2*pi*t) + 4*cos(8*pi*t);
    epoch4 = 1.5*cos(pi*t) + 4*cos(4*pi*t);
    epoch5 = 0.5*cos(pi*t) + 1.7*cos(2*pi*t) + 3.7*cos(5*pi*t);
    epoch6 = 2.3*cos(3*pi*t) + 7.8*cos(8*pi*t);
    epoch7 = 0.8*cos(pi*t) + cos(3*pi*t) + 3*cos(5*pi*t);
    y=[epoch1 epoch2 epoch3 epoch4 epoch5 epoch6 epoch7];
    figure;
    plot([1:length(y)]*0.1,y)

Hope this solves your query. MATLABhelper.com

[dpb]

Not well I think...the resolution of 0.1 isn't above Nyquist; try plotting just one section of the above and see what it appears like...

Answer 2

[dpb]

You've plotted all of them against the same time vector instead of concatenating them; hence they're all overlaying each other.

y=[epoch1 epoch2 epoch3 epoch4 epoch5 epoch6 epoch7];
plot([1:length(y)]*0.0001,y)

will give you the plot of your constructed total vector versus you're sampling time (which turns out to be 350+ units). This will still look pretty ugly owing to visual aliasing in the window (actually, it'll probably just show up as solid banded line owing to far more points in the plot than are possible to show on a monitor owing to limited number of pixels).

Answer 3

[Star Strider]

Another option that uses your original ‘t’ vector and then divides it for each section of the plot, plots each section and plots the vertical separator lines:

t = [0:0.0001:50];
inc = fix(length(t)/7);                                                 % Segments Of ‘t’

epoch1 = 0.5*cos(pi*t) + 1.5*cos(4*pi*t) + 4*cos(5*pi*t);
epoch2 = 0.7*cos(pi*t) + 2.1*cos(4*pi*t) + 5.6*cos(5*pi*t);
epoch3 = 1.5*cos(2*pi*t) + 4*cos(8*pi*t);
epoch4 = 1.5*cos(pi*t) + 4*cos(4*pi*t);
epoch5 = 0.5*cos(pi*t) + 1.7*cos(2*pi*t) + 3.7*cos(5*pi*t);
epoch6 = 2.3*cos(3*pi*t) + 7.8*cos(8*pi*t);
epoch7 = 0.8*cos(pi*t) + cos(3*pi*t) + 3*cos(5*pi*t);

epoch  = [epoch1; epoch2; epoch3; epoch4; epoch5; epoch6; epoch7];      % Matrix of ‘epoch1’...‘epoch7’

figure(1)
plot(t(1:inc), epoch(1,1:inc), '-b')                                    % Plot First Epoch
hold on
plot([1 1]*t(inc), [min(epoch(:)) max(epoch(:))], 'Color',[0.6 0.6 0.6], 'LineWidth',1)
for k1 = 2:6
    span = [1:inc] + inc*(k1-1);
    plot(t(span), epoch(k1,span), '-b')
    plot([1 1]*t(span(end)), [min(epoch(:)) max(epoch(:))], 'Color',[0.6 0.6 0.6], 'LineWidth',1)
end
plot(t(inc*k1+1:end), epoch(7,inc*k1+1:end), '-b')                      % Plot Last Epoch
hold off
axis tight

produces this plot:

Note that it does not look like the plot you initially posted (your desired signal) because you defined your signals differently.