Can someone please explain this code for me?

for i=1:ni
    for j=1:nj
        for k=1:nj
            cc(i,j) = cc(i,j)+aa(i,k)*bb(k,j);
        end
    end
end

Answer 1

[Ameer Hamza]

It is code for matrix multiplication of two matrices aa (dimensions ni*nj) and bb (dimensions nj*nj). Read here: https://en.wikipedia.org/wiki/Matrix_multiplication. Equivalent MATLAB command is

cc = aa*bb

[Nicolaas George Edward]

Thanks for your help, but I still do not understand how aa(i,k)*bb(k,j) represents a matrix multiplication. Why is it arranged that way?

[Ameer Hamza]

This portion

for k=1:nj
    cc(i,j) = cc(i,j)+aa(i,k)*bb(k,j);
end

shows that i-th row if aa is multiplied with j-th column of bb. That is how matrix multiplication is defined.

[Nicolaas George Edward]

ok thx for your help