I have the following piece of code and I am trying to calculate the coefficient matrix, a_k to solve the linear system to obtain h[n], the impulse response. I am using the inverse fast Fourier transform.
N = 9; % period is chosen to be 16
n = 0:N-1; %vector for x must start at n = 0
for k = 1:9
y3 = zeros(1,9);
y3(k+1) = N/2;
y3(N - k + 1) = N/2;
end
x3 = ifft(y3);
figure;
subplot(2,2,1);stem(n,real(x3));xlabel('n'); //line 52
ylabel('real(x3)');axis([0 N-1 -1 1]);
subplot(2,2,2);stem(n,imag(x3));xlabel('n');
ylabel('imag(x3)');axis([0 N-1 -1 1]);
subplot(2,2,3);stem(n,real(y3)/N);xlabel('k');
ylabel('real(a_k)');axis([0 N-1 -1 1]);
subplot(2,2,4);stem(n,imag(y3)/N);xlabel('k');
ylabel('imag(a_k)');axis([0 N-1 -1 1]);
However, when I run this code, I get the following error:
Error using stem (line 43)
X must be same length as Y.
Error in fft_examples (line 52)
subplot(2,2,1);stem(n,real(x3));xlabel('n');
I'm not sure where I am erring. I know that the matrix of k is from 1 through 9. Hence, I did a for loop. The y values are becoming mismatched.
size(real(x3)) % --> 1 10
size(n) % --> 1 9
So they are not the same size. You are increasing the size of y3 in y3(k+1) = N/2;
Also, why would you want to create matrix y3 in every iteration: y3 = zeros(1,9);