delay by D time samples
N-point DFT of length-L real-valued signal
DFT merging for radix 2 decimation-in-time FFT
IIR filtering in direct form -1
IIR filtering in direct form -2
dot product of two length-(M+1) vectors
DTFT of length-L signal at a single frequency w
N DTFT values over frequency range [wa, wb)
in-place decimation-in-time FFT
bit reverse of a B-bit integer n
