When is a power of , say where is an integer,
then the above DIT decomposition can be performed times, until
each DFT is length . A length DFT requires no multiplies. The
overall result is called a radix 2 FFT. A different radix 2
FFT is derived by performing decimation in frequency.

A split radix FFT is theoretically more efficient than a pure
radix 2 algorithm [71,30] because it
minimizes real arithmetic operations. The term ``split radix'' refers
to a DIT decomposition that combines portions of one radix 2 and two
radix 4 FFTs [20].^{A.4}On modern general-purpose
processors, however, computation time is often not minimized by
minimizing the arithmetic operation count (see §A.7 below).