Loop to calculate area under curve using rectangle methode

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Andre 2018-4-18

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回答： Akira Agata 2018-4-23

Hello everyone I have a graph plotted in Matlab (no function), as data was imported via Excel, I am looking for a loop to calculate the area under the curve of each interval and then add them to get the entire area

Here's how my graph look like

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Akira Agata 2018-4-18

How about using trapz function, instead of trying rectangle method. Or, do you have to try rectangle method for some reason?

https://jp.mathworks.com/help/matlab/ref/trapz.html?lang=en

Andre 2018-4-19

Actually, I have a research about the rectangular method, that's why

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Answer 1

Akira Agata 2018-4-23

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Sorry for my late response. Here is an simple example.

% Sample data
dx = pi/10;
x = 0:dx:2*pi;
y = 1+sin(x);
% integral of y = f(x) via trapezoidal method (S1) and rectangle method (S2)
S1 = trapz(x,y);
S2 = sum(y*dx);