How to find are under the curve for a random signal.

I have this random signal, is it possible that I find the are under the curve ?

Thanks for any help provided.

Answer 1

[Kaushik Lakshminarasimhan]

If samples are all uniformly spaced in time, you just need to take the sum of all elements.

area_under_signal = sum(my_signal)

Note that this number will be proportional, but not exactly equal to the actual area. If you need the exact number, you need to multiply by the temporal resolution of your signal, dt.

area_under_signal = sum(my_signal)*dt

[Karl Rueth]

Mr. Kaushik,

Thanks for your reply; when applying the "sum" method, it is giving me a vector which makes sense. However when trying to multiply it whit "dt" it is giving me an error: "Undefined function or variable 'dt'" , can you pleae guide me.

Thanks

[Kaushik Lakshminarasimhan]

Of course, you need to define it before using. You should know the temporal resolution of your signal (how frequently you sample the signal). For example, if you have a vector of time points t at which you store your EMG signal x, then you can calculate dt and then use it to compute area:

dt = median(diff(t)); %median is just to take care of rounding errors
auc = sum(x)*dt;

Answer 2

[M]

Try with this function

trapz

which does trapezoidal numerical integration.

[Star Strider]

The trapz (or cumtrapz) functions are the appropriate functions for this problem.