How to calculate Area under a curve

Hello All,

I am trying to calculate shaded area of my x and y data given in the excel sheet. I am using the following code which calculates the entire area, but I want to subtract the un-shaded area from.

x = xlsread('filename','A:A');

y = xlsread('filename','B:B')

Integral = trapz(x,y);

area(x, y);

;

Is there anyone help me with the correct code please ?. Your response will be appreciated too much.

Answer 1

[Star Strider]

Try this to get the integral only between 20 and 40:

lims = (x >= 20) & (x <= 40);
Integral = trapz(x(lims),y(lims));

[Ahmed]

Thanks a lot, truly appreciate it

[Star Strider]

As always, my pleasure!

Answer 2

[Elnaz Ensafi]

I have plot that I extracted from EEG data. I would like to extract area under the curve from 25 ms to 275 ms. could you Please help me in this case?