How can I flip the top area of the peak that is going down?
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Hi, I would like to flip the part of the peak that goes gown so its pointed upward. I want there to be a space between the data where the top-points are to mark that this was the end-points and that the top peak goes upward instead of downward.. how can you do this?
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/149789/image.jpeg)
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Image Analyst
on 5 May 2015
For one such section, this should work (untested):
peakValue = max(signal);
index1 = find(signal > (peakValue - 0.001), 1, 'first')
index2 = find(signal > (peakValue - 0.001), 1, 'last');
signal(index1:index2) = 2 * peakValue - signal(index1:index2);
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Image Analyst
on 5 May 2015
It's basically finding the distance between the max (top of the box) and the signal below the top of the box. Maybe if I did it more explicitly like this
delta = abs(peakValue - signal)
% Now add the delta to a vertical offset of peakValue
newSignal = peakValue + delta
but if you do the math you get
newSignal = peakValue + peakValue - signal
newSignal = 2 * peakValue - signal
So that's how I got the formula.
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