For audio decoding, the butterfly unit determines combinations of components of {TAIL ~ a frequency domain vector} to reduce the number of {HEAD ~ multiplies} required to transform to the time domain  
For audio decoding , the butterfly unit determines combinations of components of { TAIL ~ a frequency domain vector } to reduce the number of { HEAD ~ multiplies } required to transform to the time domain
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH