ðə splˈɪtɹˈeɪdɪks ˈælɡɚɹˌɪθəm kæn ˈoʊnli biː ɐplˈaɪd wɛn ˈɛn ɪz ɐ mˌʌltɪpəl ʌv fˈoːɹ, bˌʌt sˈɪns ɪt bɹˈeɪks ɐ dˌiːˌɛftˈiː ˌɪntʊ smˈɔːlɚ dˌiːˌɛftˈiːz ɪt kæn biː kəmbˈaɪnd wɪð ˌɛni ˈʌðɚɹ ˌɛfˌɛftˈiː ˈælɡɚɹˌɪθəm æz dɪzˈaɪɚd.
The split-radix algorithm can only be applied when N is a multiple of 4, but since it breaks a DFT into smaller DFTs it can be combined with any other FFT algorithm as desired.