how to find rows and columns without using size

Introductory MATLAB course, haven't covered loops and such yet. I'm curious how to find rows + columns of an array without using size fxn? Obv numel()/length() give you rows + columns, but they don't tell you which is which. What to do next?

[Adam Danz]

Why not use the size function?

If the input is a matrix you could do this (below, but there might be better methods) but again, why?

m = rand(5,12);   % demo input 

m(isnan(m)|m==0) = 1; % replace NaNs & 0s with any value
sz = [mode(sum(m./m,1)), mode(sum(m./m,2))]

% or
sz = [mode(sum(m./m,1)), mode(sum(m./m,2))]

[Hanwool Yun]

I'm not allowed to use the size fxn.

[Guillaume]

What is the actual text of the assignment, not your interpretation of it?

An assignment that asks you to find the size of a matrix without using the size function would be completely absurd. Sure you can find all sorts of roundabout ways of doing it, none of which would teach you anything useful and all of them requiring more advanced knowledge than the size function.

[Adam Danz]

^^ my thoughts exactly.

Answer 1

[Bruno Luong]

for 2D array

p=numel(A);
if p==0
    try
        r = A(1,:);
        n = 0;
        m = numel(A*zeros(0,1));
    catch
        m = 0;
        m = numel(zeros(1,0)*A);
    end
else
    m = numel(A(:,1));
    n = p/m;
end

[Hanwool Yun]

unfortunately we haven't covered loops yet, is there any way to do this with basics, like using length and numel and indexing?

[Bruno Luong]

loop? which loop?

Answer 2

[Bruno Luong]

[numel(prod(A,2)) numel(prod(A,1))] % prod instead of sum for a change