MATLAB: How to calculate partial area-under-the-curve

aucplottrapz

Hi all,

I am trying to find the area under the curve (AUC) for a part of a graph. I use "trapz" function, but this function calculates the AUC for a entire area below the selected part of the graph. Any hint how I can calculate only part of it (not entire part until x-axis)? Please see figure. Interested are to be calculate is in red.

Thanks, Mehdi

(for simulation of data, just generate a random vector and try a part of it.)

Best Answer

Mehdi, use trapz twice to subtract the area below the red marked one (between x-axis and data points y = 0.3111, 0.1848 ) from the entire area.

Related Solutions

MATLAB: How to calculate partial area-under-the-curve

Use trapz twice, once to integrate (A, B, C), and again to integrate (A, C).

Then subtract the (A, C) result from the (A, B, C) result.

It would definitely help to have the data, preferably as a .mat file.

MATLAB: Value of x for which AUC reaches a given value

‘I calculate the AUC using the trapz function.’

That being the problem. Use cumtrapz instead:

t = linspace(0, 1, 500);                        % Create Data

x = rand(size(t));                             % Create Data
AUC = cumtrapz(t,x);
AUC50 = interp1(AUC, t, AUC(end)/2);
figure
plot(t, AUC)
hold on
plot(AUC50, AUC(end)/2, 'p')
hold off
text(AUC50, AUC(end)/2, sprintf('\\leftarrow AUC = %.2f at %.2f', AUC(end)/2, AUC50), 'HorizontalAlignment','left', 'VerticalAlignment','middle')

Best Answer

Related Solutions

MATLAB: How to calculate partial area-under-the-curve

MATLAB: Value of x for which AUC reaches a given value

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