FFT Kernel

How to find the Kernel that is used in Matlab for doing FFT. For eg. a = [2 2; 0 1] and when I call b = fft2(a), I get the result as [5 -1;3 1].

How to find the kernel matrix that is used for FFT calculation.

Answer 1

[Wayne King]

Hi The 2D DFT computes the DFT (as defined by the equation in the fft documentation) on the columns of a, and then it computes the DFT on the rows of that output. So

   a = [2 2; 0 1];
   b = fft2(a);

is equivalent to

   b1 = fft(a); % compute DFT of the columns of a
   b2 = fft(b1.'); % compute DFT of rows of b1

Answer 2

[Malathy]

Kernel used is [ 1 1; 1 -1]

[Palguna Gopireddy]

how?