Hi Mads,
In my understanding you want to obtain all the information from a matrix using loops.
Here is an example that shows the use of code provided by you on a sample matrix "q" and sample time vector "t":
% Sample time vector
t = linspace(0, 10, 1000); % 0 to 10 seconds, 1000 points
% Sample matrix q with sinusoidal columns of different frequencies
q = [sin(2 * pi * 1 * t); sin(2 * pi * 1.5 * t); sin(2 * pi * 2 * t)]';
% Note: q is transposed to match the expected dimensions (rows are time points)
% Initialize cell arrays to store maxima and minima information
Maxima = cell(1, size(q, 2));
MaxIdx = cell(1, size(q, 2));
Minima = cell(1, size(q, 2));
MinIdx = cell(1, size(q, 2));
% Loop through each column of q
for i = 1:size(q, 2)
[maxima, maxIdx] = findpeaks(q(:,i));
[minima, minIdx] = findpeaks(-q(:,i)); % To find minima
% Store in cell arrays
Maxima{i} = maxima;
MaxIdx{i} = maxIdx;
Minima{i} = -minima; % Convert back to positive values
MinIdx{i} = minIdx;
end
% Plotting
figure; hold on
% Iterate over each column's results to plot
for i = 1:size(q, 2)
plot(t(MaxIdx{i}), Maxima{i}, 'o', 'MarkerEdgeColor', 'r');
plot(t(MinIdx{i}), Minima{i}, 'o', 'MarkerEdgeColor', 'b');
end
plot(t, q) % Plot the original sinusoidal waves
xlabel('Time (s)');
ylabel('Amplitude');
title('Maxima and Minima of Sinusoidal Waves');
legend({'Maxima', 'Minima', 'Waveforms'}, 'Location', 'best');
grid on;
Refer to the following documentation to know more about cell arrays:
Hope this resolves your query!
Thanks
