MATLAB: DSP

hello everybody how can I find the time at which the maximum value of the signal happen, if I have signal of 2D ,one is the time and the other is the amplitude .

Best Answer

[maxval, maxidx] = max(YourSignal(:,2));  %assuming 2nd col is ampl
time_at_max = YourSignal(maxidx,1);       %assuming 1st col is time

Related Solutions

MATLAB: Returning Position in Array or Matrices for max()

[maxval, maxidx] = max(YourMatrix(:));
[row, col] = ind2sub(size(YourMatrix), maxidx);

MATLAB: How to find minimum Pixel value

You should be able to do

	minValue = min(thisImage(:))
	[row, column] = find(thisImage == minValue);

for each time point (slice of your 3-D image volume). Here is a full demo:

imgfilt = randi(65535, 64, 64, 1913); % Create sample data.  You, of course, would use your own.
imgfilt(44:66) = nan;
[rows, columns, numberOfTimePoints] = size(imgfilt)
for slice = 1 : numberOfTimePoints
	% Get the image for this time point.
	thisImage = imgfilt(32:end, 32:end, slice);
	minValue = min(thisImage(:));
	[row, column] = find(thisImage == minValue);
	% To get original indices, need to add 31 to the row and column
	row = row + 31;
	column = column + 31;
	% Store the rows and columns where this time point image equals the min.
	% We are using a cell array because each image may have a different number 
	% of locations where the min occurs.
	ca{slice, 1} = row;
	ca{slice, 2} = column;
	% For fun, print them out.
	for k = 1 : length(row)
		r = row(k);
		c = column(k);
		fprintf('For time point %d, the min value of %f occurs at row %d, column %d.\n', ...
			slice, imgfilt(r, c, slice), r, c);
	end
end

Best Answer

Related Solutions

MATLAB: Returning Position in Array or Matrices for max()

MATLAB: How to find minimum Pixel value

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