Radix-2 FFT

Small library for in-place bit reversed DIT DFT radix-2 FFT. Functions are provided for 1D and 2D FFTs as well as fftshift and fftshift2 which rearranges the components to place the 0 frequency term in the centre.

FFT/iFFT

An example using the 1D transform is as follows:

int N = 4;

float xr[N] = {1,2,3,4};
float xi[N] = {5,6,7,8};

rad2FFT(xr,xi, N);

which is transforming sequence (1+5i, 2+6i, 3+7i, 4+8i). The inverse transform is given by

irad2FFT(xr,xi, N);

The same is true for rad2FFT2 which has decloration

void rad2FFT2(float **xr, float **xi, unsigned int Nx, unsigned int Ny);

with inverse

irad2FFT2(xr,xi, Nx, Ny);

FFF shift

Fftshift has header

void fftshift(float xr[], float xi[], unsigned int N);