z-transform DFT filters and FFT's

The paper shows how discrete Fourier transformation can be implemented as a filter bank in a way which reduces the number of filter coefficients. A particular implementation of such a filter bank is directly related to the normal complex FFT algorithm. The principle developed further leads to types of DFT filter banks which utilize a minimum of complex coefficients. These implementations lead to new forms of FFT's, among which is acos/ for a real signal which only employs real coefficients. The new FFT algorithms use only half as many real multiplications as does the classical FFT.