Certain filter design software can result in small non-zero values for the odd terms in the half-band filter impulse response. In this situation, it can be useful to force these values to 0 and re-evaluate the frequency response to assess if it is still acceptable for the intended application. If the odd terms are not identically zero, the hardware optimizations described previously are not possible. If the small non-zero value terms cannot be ignored, the general polyphase decimator or interpolator described in Polyphase Decimator and Polyphase Interpolator , using a rate change of two, is more appropriate.