Calculate area under peak

I am trying to find the area under the curve as shown in the image. I found the peaks of the signal and plotted the line on the signal. I am looking to calculate the area shaded in green for the entire signal. I have no idea how to do this. Any ideas are welcomed. Thank you

[Dyuman Joshi]

For the 3rd area from left, why is the area not a triangle and a quadrilateral?

Because the 4th point is higher than 3rd point?

Answer 1

[Timo Dietz]

Not sure whether I got your issue.

What about resampling (resample command) the red and blue trace to the same x step size.

Then, you only have to subtract the area under the red from the area under the blue trace, respectively, just subtract all indiviudal data points and sum up the differences. To achieve the area you certainly have to finally multiply by the x step size.

[Timo Dietz]

Note, that the accuracy of the area calculation is certainly limited to the chosen x step size (discrete values).

Answer 2

[KSSV]

Read about the functions polyarea, trapz. Provde the (x,y) data of the curve for which you want to calculate the area.