# It is possible to obtain non-zero padding fft from zero padding fft?

This is just a question out of my curiosity, normally we do not do this I have a x(n)=[1 2 3]

y(n) = fft[1 2 3 0] =  6 + 0i  -2 - 2i   2 + 0i  -2 + 2i %zero padding
y'(n) = fft([1 2 3]) = 6 + 0i  -1.5 + 0.87i  -1.5 - 0.87i


I used Matlab to generate these results. My question is there way to obtain y'(n) from y(n)?

• You mean other than taking the inverse fft, removing the zeros and then doing another fft? – Aaron Dec 10 '13 at 19:41
• yes, some kind of direct calculation – user7226 Dec 10 '13 at 19:43