9.2 decimation-in-time FFT Algorithms DIT flow graph for 8-point decimation in time x[0] X[O] N=8=23 generalized to x[4 PX1川 w N=2m x[2]o pX[2] W m=1og2N x[6]o- X3] WN x[1]o X[4] m级：每级乘法 w 和加法个数为N →X[5] x3) s6] WS-Wwxn Complexity: 。x] w WN Nlog2N complex multiplications and Nlog2N additions Nm Nm D424 9.2 decimation-in-time FFT Algorithms ◆DIT flow graph for 8-point decimation in time ◆Complexity: Nlog2N complex multiplications and Nlog2N additions 2 WN 0 WN 4 WN 6 WN N=2m m=log2N N=8=23 2 WN 6 WN generalized to m级: 每级乘法 和加法个数为N 2 /2 N =W WN N 2 /2 N W WN N = Nm Nm