Trapezoidal rule with unevenly spaced data points
65 views (last 30 days)
Show older comments
I am having a lot of trouble using the trapezoidal method on matlab to determine the area under the curve with no function, just unevenly spaced data points:
(0,0), (1,5), (5,8), (9,6), (3,10), (0,11)
I have absolutely no idea where to start.
6 Comments
James Tursa
on 22 Sep 2022
Edited: James Tursa
on 22 Sep 2022
@Georgia Platt If you know how to do it by hand, why can't you code that method into MATLAB? Especially once you look at the formulas in the links above. For two points (x1,y1) and (x2,y2) with the ordering x1<x2, the area formed by the trapezoid is simply (x2-x1)*(y1+y2)/2, so why can't you write a loop to sum these up?
Walter Roberson
on 22 Sep 2022
You can decompose into shapes. There is an initial triangle, and you can get the area for that as 1/2 base times height. There are then a series of trapazoids, and you can calculate their areas. Then there is a final triangle and 1/2 base times height for it. Add the areas all together.
... which is what trapz() will do for you.
Answers (1)
See Also
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!