fftdemo15.m

% The 3D function
z = zeros(16,32); z(2:3,2:3) = ones(2);
Nx = size(z,2);
Ny = size(z,1);

% Plot surface
figure
subplot(2,1,1), surf(z)
view(0,90), title('Unshifted Signal')
xlabel('x')
ylabel('y')

% Frequency domain samples
fx = 0:Nx-1;
fy = 0:Ny-1;

% The shifts
kx = 10;
ky = 4;

% The exponentials
shft_x = exp((-2*pi*i/Nx)*kx*fx);
shft_y = exp((-2*pi*i/Ny)*ky*fy);

% The shift matrix
shft = shft_y.'*shft_x;

% The shifting operation (notice that fft2 is used for a 2D FFT)
Z = fft2(z);
Zshft = Z.*shft;
zshft = real(ifft2(Zshft));

subplot(2,1,2), surf(zshft)
view(0,90), title('Unshifted Signal')
xlabel('x')
ylabel('y')