# Subtract two values of an array and multiply them by a constant

2 views (last 30 days)
Troth on 1 Dec 2022
Commented: Troth on 1 Dec 2022
A = B_Oscilloscope; % Data (1007x94 array)
for k = 1:size(A,2)
[pks, locs] = findpeaks(A(:,k));
[~,ix] = sort(pks);
minpk{:,k} = [pks(ix(1:2)) locs(ix(1:2))];
maxpk{:,k} = [pks(ix(end-1:end)) locs(ix(end-1:end))];
end
maxpk{1} % View Result
minpk{1} % View Result
Hi everyone! Here is my current code:
This creates 2 1x94 arrays with my data (Minimums and Maximums), and each cell contains a 2x2 matrix (second peak and its indice, and first peak and indice). I need to go into each of those matrixes in the arrays and subtract the second entry in the first row by the second entry in the second row, and multiply it by a constant. Similary for both of the arrays I need to subtruct the 1st entry in the minmum row from the 1st in the second, the 2nd entry in the minimum row from the 2nd in the maximum row.
I hope that makes sense.
Fifteen12 on 1 Dec 2022
It might help if you provide an example of what you'd like to do! Is the constant scalar the same for every cell?
Troth on 1 Dec 2022
Yes, the constant scalar is the same

Fifteen12 on 1 Dec 2022
Edited: Fifteen12 on 1 Dec 2022
If you put everything into an array (rather than a cell array) you can do logial indexing:
rng(1);
constant = 2;
minpk = [randi(10, 2), randi(10, 2), randi(10, 2)]
minpk = 2×6
5 1 2 2 4 5 8 4 1 4 6 7
out = constant * (minpk(1, 2:2:length(minpk)) - minpk(2, 2:2:length(minpk)))
out = 1×3
-6 -4 -4
Troth on 1 Dec 2022
For some reason turning it into an array never even occured to me and would make it much easier, thank you!

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