Vectorize nested for loops

Hi everybody,

I am currently trying to vectorize the following nested for loop:

% Definitions
x = 10;
A = zeros(3,10000);
B = zeros(3,5000);
C = zeros(1,5000);

% .....
% A and B are filled
%.....

% Loop

for i=1:length(A)
    for k=1:length(B)
        if(A(:,i) - B(:,k) <= x)
           C(k) = true;
        end        
    end
end

In the end it is intended to use B matrices with much more elements, e.g. B = 3 x 10e06.

That's why I would like to speed up the process, vectorizing it.

Thanks in advance!

Answer 1

[KSSV]

You can reshape the matrices and get what you want. But note that, C will be over written when i-index changes.

You may proceed something like shown.

A1 = reshape(A,3,1,10000) ; 
C = A1-B<=x ; 

Now think of C.