How do I write a function to find 4 consecutive numbers in a square matrix which would give the largest product?

I think I should be using for loops but I'm very confused how to write them in this case.

    function y=hardstuff(a)
    x=size(a)
    if x(1)~=x(2)
        error 'Matrix not square'
    elseif x(1)<=3
        error 'Matrix too small'
    end
    b=a(1,:)
    c=length(b)
    d=1

    for i=1:4
        d=d*a(i)

    end

[Cedric]

If it's for a homework, with small size arrays, you could start sorting elements ( doc sort ), and then implement some loop starting from the largest element, and figuring out if the current element plus the next 3 are consecutive numbers.

Answer 1

[Matt J]

Hint: here's a loop-free method to obtain all products of 4 consecutive elements,

 T= conv2(log(a),[1 1 1 1].','valid');
  T=real(exp(T));

There is no assumption here that the elements are positive.