MATLAB: Matrix indexing problem, column-major

Question

Trying to take an input vector or matrix and form new 2×2 matrix from the row,column index for each element of the input vector/matrix where the element is less than the product of the element's row and column, with output in column-major order. Example: Input [1 1;0 4;6 5] would output [2 1; 1 2;3 2].

My code:

function [A] = small_elements(X)
A = [];
[r,c] = size(X);
    for xc = 1:c
        for xr = 1:r
            if X < (xr*xc)
                A = [A;[xr;xc]];
            end
        end
    end
end

I was formerly getting a lot of syntax errors. My output has consistently been the empty set. Trying to see why xr;xc is not entering into A.

Answer 1

            if X(xr,xc) < (xr*xc)   % <-- changed X to X(xr,xc)
                A = [A;[xr,xc]];    % <-- changed [xr;xc] to [xr,xc]
            end