# Optimise comparing multidimensional matrices

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Anna on 22 Apr 2022
Edited: Bruno Luong on 23 Apr 2022
Hi. I'm trying to see where in a cell array of 21449x15, in which each cell contains a matrix of 1x7, each line of a matrix of 116255x7 occurs. Below is what I have as nested loops. It works as expected, however is obviously very slow. I'm struggling to apply any common optimisation techniques such as vectorisation or creating functions to this multidimensional problem. Would anyone have any advice please?
for i = 1:21449
% For each formula from b1 to b15
for j = 1:15
% Skip empty cases
if ~any(pep{i,j})
continue
else
% For every formula in the MFP output
for k = 1:length(formulas)
% Check if the same formula exists in the database
if isequal(formulas, pep{i,j})
% If match found, replace the formula by a score, the
% higher the number in the sequence, the higher the
% score.
result(i,j) = 1*j;
else
continue
end
end
end
end
end
##### 2 CommentsShowHide 1 older comment
Anna on 23 Apr 2022
Thank you, that's correct, it should read formulas(k,:), I'm sorry. I have accepted the solution posted below.

Bruno Luong on 22 Apr 2022
Edited: Bruno Luong on 23 Apr 2022
I simply code by guessing what you have behind de scene. You better tell us exactly what are class/size of the variables in your pseudo code, for example the k loop doesn't oddly extract any elements from "formulas".
result = zeros(size(pep));
database = cat(1,pep{:});
tf = ismember(database, formulas, 'rows');
tf = reshape(tf, size(pep));
[~,j] = find(tf);
result(tf) = 1*j;
Anna on 23 Apr 2022
First of all I apologise for the quality of my question, I must have accidentally deleted the (k,:), it should read formulas(k,:).
Second of all, your solution is exactly what I was after! Thank you very much. Reshaping the array didn't even occur to me, that's very clever.

R2021a

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