Plotting the integral of a graph

Hi,

I have a graph of a waveform that I want to find the integral plot of this waveform (shown below). Could this be done on MATLAB or is this something for Simulink. I am new to Simulink, and I would appreciate any help on graphing the integral plot.

Answer 1

[Fabio Freschi]

Suppose that x and y are the vectors defining your waveform.

% dummy values
x = linspace(0,2*pi,1000);
y = sin(x);

% integral
Y = cumtrapz(x,y);

% plot
figure, hold on
plot(x,y); % waveform
plot(x,Y); % integral
legend('waveform','integral')

[Hans123]

thank you Fabio! I just want to verify the plot I got is the integral - what would be the code to derive Y so I could plot it and verify it is the same as the initial plot.

[Fabio Freschi]

My pleasure! The derivative can be obtained with diff function.

yd = diff(Y)./diff(x);

% yd has one point less, so we must calculate an ad-hoc x vector
xd = (x(1:end-1)+x(2:end))/2;

% plot
plot(xd,yd);

It this solves your original question, please accept it!

F