FFT-Introduce Digital Signal Processing--DFT/FFT Algorithms DFT plays an important role in the analysis,design,and implementation of discrete-time signal-processing algorithms and systems.Because direct computing DFT needs N2 complex multiplication,when N is larger, computation cost is larger.Before FFT comes,it is not practical that using DFT spectrum analysis and real-time processing of signal.Until in 1965 fast computation algorithm turn up,situation didn't change (J.W.Cooley,J. W.Tukey,G.Sande). 上浒充通大Digital Signal Processing—— DFT/FFT Algorithms FFT- Introduce DFT plays an important role in the analysis, design, and implementation of discrete-time signal-processing algorithms and systems. Because direct computing DFT needs N2 complex multiplication ， when N is larger， computation cost is larger. Before FFT comes，it is not practical that using DFT spectrum analysis and real-time processing of signal 。 Until in 1965 fast computation algorithm turn up，situation didn’t change (J. W. Coo1ey, J. W. Tukey, G. Sande)