Find the indices of elements of matrix that were multiplied

I have a task to find the maximum product of elements in a matrix. The input arguments are the matrix and the scalar n that tells me how many elements to multiply. If n=2, then I should multiply two by two. The maximum product can lie either in rows, or in columns on in diagonal. For example in this case A's elements were multiplied 2 by 2 along rows (B) and columns (C).

A =

       8     1     6
       3     5     7
       4     9     2

B =

      8.0000    6.0000
     15.0000   35.0000
     36.0000   18.0000

C =

     24.0000    5.0000   42.0000
     12.0000   45.0000   14.0000

I do it using the loop

c=[]

for ii = 1:(length(A)-n+1)
    p = prod(A(:,ii:ii+n-1));
    c=[c p];
end

or

for i=1:size(A,2)
      B(i,:)=real(exp(conv(log(A(i,:)),ones(1,n),'valid')));
      C(:,i)=real(exp(conv(log(A(:,i)),ones(1,n),'valid')));
end

In both cases I receive the product but when it comes to getting the maximum among that products, (in my case that is the product of A(3,1)*A(3,2)=45) I cannot find the indices of original matrix elements that formed that product. Any help will be appreciated.

Answer 1

[Andrei Bobrov]

A =[   8     1     6
       3     5     7
       4     9     2];
n = 2;

s = size(A);
B = real(exp(conv2(log(A),ones(1,n),'valid')));
C = real(exp(conv2(log(A),ones(n,1),'valid')));

[b,bm] = max(B(:));
[c,cm] = max(C(:));
if b > c
    [ii,jb] = ind2sub([s(1),s(2) - n + 1],bm);
    out = {ii,jb + (0:n-1)};
else
    [ic,jj] = ind2sub([s(1) - n + 1,s(2)],cm);
    out = {ic + (0:n-1),jj};
end