How can I plot slope including maximum peaks?
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Hello, How can I plot slope including peaks point? It should look like exp. I tried envelope but It does not work for my code.
Thank you.
采纳的回答
Star Strider
2017-12-13
编辑：Star Strider
2017-12-13
If you have the Signal Processing Toolbox, use the findpeaks function to define the peaks and their locations. You can then use those values directly in your exponential regression.
EDIT —
Try this:
y = [12 14 2 8 9 4 6 7 9 5 6];
x = 1:length(y);
ym = mean(y);
yz = y - ym; % Create Symmetry About Mean
[pospks, poslocs] = findpeaks(yz); % Positive Peaks & Locations
[negpks, neglocs] = findpeaks(-yz); % Negative Peaks & Locations
pkvct = [pospks negpks]; % Combine In One Vector FOr Sorting
[locs,idx] = sort([poslocs neglocs]); % Sort
pks = pkvct(idx);
objfcn = @(b,x) b(1).*exp(b(2).*x); % Exponential Objective Function
[B,resnorm] = fminsearch(@(b) norm(pks - objfcn(b,locs)), rand(2,1)); % Fit Data (EStimate Parameters)
figure(1)
plot(x, y, '-g')
hold on
% plot(locs, pks+ym, 'pg')
plot(locs, objfcn(B,locs)+ym, '-r')
hold off
text(5, 13, sprintf('y(x) = %.3f + e^{%.3f\\cdotx} + %.3f', B, ym))
2 个评论
Ezgi Ertunç
2017-12-14
Star Strider
2017-12-14
My pleasure.
If my Answer helped you solve your problem, please Accept it!
更多回答（1 个）
Image Analyst
2017-12-13
Why would you try envelope()? diff() would give the slope
slopes = diff(y)
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