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Area under curve (no function)

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Rick
Rick 2014-9-9
评论： Star Strider 2021-1-16
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
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Samarth Patil
Samarth Patil 2018-6-7
how to find the area in an interval for such a plot?
Krishnendu Mukherjee
Krishnendu Mukherjee 2018-9-12
Thanks a lot. It helped a lot.

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采纳的回答

Star Strider
Star Strider 2014-9-9
编辑：Star Strider 2014-9-9
Use trapz. It’s designed to do exactly what you want.
Int = trapz(X, -1./rA)
produces:
Int =
306.7455
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Saurabh Parmar
Saurabh Parmar 2020-5-25
Thank You So Much! That helped a lot.

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更多回答（1 个）

Ashok
Ashok 2016-7-9
% 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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