Hello, im a physics engineering student and i need a little help with fft function. I wrote the following code everything works, but when i get the fft. I was supose to obtain a sinc function and if you take a close look, it is a sinc, but in the wrong points, can anyone help me with this? if you dont know/remember what a sinc function looks like: https://www.google.pt/search?q=3d+s...%2Fwiki%2FFile%3AMatlab_surf_sinc.svg;561;420 x0=0; y0=0; dx=5; dy=5; px=0.05; py=0.05; dxx=1; dyy=1; n=dx/px+1; m=dy/py+1; xx=-dx/2:px:dx/2; yy=-dy/2:py:dy/2; [X,Y]=meshgrid(xx,yy); Z=zeros(n,m); %w=X.^2+Y.^2; for i=1:n for j=1:m if X(i,j)>=x0-dxx/2 && X(i,j)<=x0+dxx/2 && Y(i,j)>=y0-dyy/2 && Y(i,j)<=y0+dyy/2 Z(i,j)=1; end end end A=fft(Z); B=A.*conj(A); figure(1) surf(X,Y,Z) colormap jet colorbar figure(2) surf(X,Y,B) colormap jet colorbar Also, how i make sure that Z, has always the size of the matrixs X and Y?