How to interpolate a graph to find a point halfway from the max peak

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Graham Boag 2011-2-24

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Hi, I am wondering how to find a point halfway from the maximum point (thats pointing down the way) on the graph I created:

http://www.2shared.com/photo/pIak1Za9/graph1.html

It was made using the code

I = imread('f_000021.tif','TIFF'); imshow('f_000021.tif') x=[128 180]; y=[50 50]; improfile(I,x,y) plot(max)

There isn't many pixels plotted so I was wondering if I could pick a point in between a couple of pixels on that graph (half of the maximum value)?

Thanks, Graham

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Graham Boag 2011-2-24

Yes I think so, Sorry its not so easy for me to convey what I am trying to do - my mathematics language is not so good!

Jan 2011-2-24

No problem. Finding a solution is often a iterative process, which clears the question at first. If the question is absolutely and mathematically clear, the solution is usually found already.

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采纳的回答

Jan 2011-2-24

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1945-how-to-interpolate-a-graph-to-find-a-point-halfway-from-the-max-peak#answer_2887

在 MATLAB Online 中打开

Do you search for something like this?

V = sin(0:0.01:pi/2);
maxV = max(V);
minV = min(V);
Range = maxV - minV;
HalfIndex = find(V > maxV - Range / 2, 1, 'first');

You have to adjust the signs and > or < according to your exact problem.

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Graham Boag 2011-2-24

Thanks, I will have a play around and see what I get!

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