For loop keeps repeating same value

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Safwan
Safwan 2016-11-21
评论： Walter Roberson 2016-11-23
I am trying to write a code that finds all maximum values above threshold. What I am trying to do is find the maximum value, make it zero or remove it, find the next maximum value until all maximum values above threshold are identified. But, pdpulse(n,:) = c keeps repeating the same value which the first maximum value in x. I think the problem comes from the loops but I can't figure out why and how to fix it.
x = Data(:, 1); % import Y of column 1 from Data
for n = 1:2000
[M,I] = max (x);
if M > 2
c = x(I-299 : I+700); % range of maximum values i.e. pre and post processing
c = c'; % transpose
pulse(n,:)= c; % n-th row of pulse
end
M = 0;
end
Thank you

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回答（1 个）

Walter Roberson
Walter Roberson 2016-11-21
Your c = x(I-299 : I+700) does not depend upon your loop variable n and does not depend upon any value that is changing in your loop, so it is always going to have the same result.
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Safwan
Safwan 2016-11-22
This is actually pretty dumb but I don't quite understand how this line works but I know it provides me the range I want for one maximum value
c = x(I-299 : I+700)
Walter Roberson
Walter Roberson 2016-11-22
That code is not finding values above a threshold: it is finding values in a window 1000 wide near the current maximum. It could fail if the location of the current maximum is within 299 of the beginning or within 700 of the end. If you were iterating setting maxima to no longer be considered, you would run the risk that your flag value (e.g., -inf or nan) would be within the range as well.
If you want to find all maximum values over a threshold then,
x(x >= TheThreshold)
would give you that. If you wanted them in decreasing order, then sort() with 'descend'

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