Calculation of a given area using the trapz

Hello, to calculate the total area I used the trapz and it worked, but I can't do it for a certain area (figure above inside the red rectangle). If you can calculate, do I use trapz or do I use another? Show me how you do, please.

Thanks

Answer 1

[Jon]

You need to limit the range of x and y that are fed to trapz, you could do something like this, assuming your original variables are called x and y (modify accordingly for your actual variable names)

% assume x and y are defined earlier

% define range of interest
xRange = [21,31.3]

% find logical indices for range of interest
idl = x >= xRange(1) & x <= xRange(2);

% provide just values of interest to trapz
A = trapz(x(idl),y(idl))

[Jacqueline Rigatto]

Thanks for the help, Jon

[Jon]

Your welcome