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Area under curve (no function)

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Rick
Rick on 9 Sep 2014
Commented: Star Strider on 16 Jan 2021
Hello,
If I have a set of data such as
X = [0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.85];
rA = [-.0053, -.0052, -.0050, -.0045, -.0040, -.0033, -.0025, -.0018, -.00125, -.0010];
plot(X,-1./rA)
and I want to know the area under the curve generated in the graph, how would I do that? There is no function involved here, this is just raw data, so I know I can't use quad or any of those integral functions.
Thanks
  3 Comments
Krishnendu Mukherjee
Krishnendu Mukherjee on 12 Sep 2018
Thanks a lot. It helped a lot.

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Accepted Answer

Star Strider
Star Strider on 9 Sep 2014
Edited: Star Strider on 9 Sep 2014
Use trapz. It’s designed to do exactly what you want.
Int = trapz(X, -1./rA)
produces:
Int =
306.7455
  5 Comments
Star Strider
Star Strider on 16 Jan 2021
Everyone — My pleasure!

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More Answers (1)

Ashok
Ashok on 9 Jul 2016
% Find the number of pixels of the connected component
Bin_image - logical binary image CC = bwconncomp(Bin_image); CC numPixels = cellfun(@numel,CC.PixelIdxList); disp(numPixels);
% Find the number of pixels of the connected component
[Label,~]=bwlabel((Bin_image),8); [Label,~]=bwlabel(Bin_log_4mult,8); num=1; [row, ~] = find(Label==num); Obj_area=numel(row); display(Obj_area);

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