why there are 0's in my matrix?

I have been woriking on my assignment and i am trying to make a matrix. the code is on the roght hand side. i think i coverd everythings but why there are 0's in my matrix? Doesn't make any sense.

here's my code

N = 5;
A = zeros(2*N+1,2*N+1);
for i = 2:N+1
    t(i-1) = i-1;
    A(1,1) = N;
    A(1,i) = sum(sin(i*t(i-1)));
    A(1,i+N) = sum(cos(i*t(i-1)));
    for j = 1:N+1
        A(i,j) = A(1,j)*A(1,i);
        A(i,j+N) = A(1,j+N)*A(1,i);              
        A(i+N,j) = A(1,j)*A(1,i+N);
        A(i+N,j+N) = A(1,j+N)*A(1,i+N);
    end
    
end

[Rik]

Please post your code as code. You can simply copy-paste, we would have to type in everything by hand. Have a read here and especially here.

Answer 1

[Cris LaPierre]

You predefine your matrix A as zeros. So when you get to an equation that multiplies the original value in A to create the new value, the result is 0.

A(i,j) = A(1,j)*A(1,i); % When i=2 and j>2, i=3 and j>3, etc.

[Charles Gao]

That makes a lot of sense! Thank you so much!!!!