how can i make the centre elements of a matrix to become zeros

I am writting a function that takes an n-by-m matrix and and an odd interger k as input arguments. both n and m are odd numbers as well and are all bigger than k. the function should return the input argument with its center k-by-k matrix zeroed out. this is how my function looks like currently and it is not producing the correct output. please help.

function A= cancel_middle(A,k)

for ii=1:k

for jj=1:k

A(end/2+1/2:end/2+1/2)=0;

end

end

end

Answer 1

[Jan]

The body of the loop does not use the indices ii and jj at all, so the code does not depend on k in any way.

Call size at first to determine the dimension of A. Then find out, which indices will be affected, if you need k rows and columns at the center. You do not need loops to assign the zeros, but the approach A(c1:c2, r1:r2) = 0 is sufficient.

Answer 2

[Elijah Smith]

this is what I came up with:

function A = cancel_middle(A, k)
    [n, m] = size(A);
    array2add = zeros(k);
    if n > k && m > k
        A((floor(n/2) - floor(k/2) + 1):(floor(n/2) - floor(k/2) + k), (floor(m/2) - floor(k/2) + 1):(floor(m/2) - floor(k/2) + k)) = array2add;
    end
end

it just replace the middle k-by-k matrix with zeros and if the rows/cols are add it defaults to the top left.

[Weisz Thomas]

thank you very much. it is working perfectly.

Answer 3

[Image Analyst]

Try getting rid of the for loops and just finding the middle element and setting it to zero

middleLinearIndex = ceil(numel(A) / 2);
A(middleLinearIndex) = 0;