bitrev.c - bit reversed index 
complex.c - complex arithmetic in C 
cmplx.h - header file for complex.c 
dft.c - DFT 
dftmerge.c - DFT merging 
dtft.c - DTFT at single frequency 
dtftr.c - DTFT over frequency range 
fft.c - FFT 
ifft.c - inverse FFT 
modwrap.c - modulo-N reduction 
shuffle.c - shuffling in FFT 
swap.c - swapping in FFT