fft(快速傅立叶变换)（FFT (fast Fu Liye transform)）.docVIP

fft(快速傅立叶变换)（FFT (fast Fu Liye transform)） Requirements: the preparation of any 2 integer power points based -2 DIT-FFT and DIF-FFT general C/C++ program to verify its correctness, and direct calculation of DFT points 2^N (N=10,.16...) when the running time difference. #includeiostream #includefstream #includecomplex #includetime.h #includemath.h #define PI 3.14159 Typedef unsigned int UINT; Using namespace std; UINT RevBit (UINT n, int r) / / bit reverse function { UINT temp = n; Temp = (temp 0 1 | (temp 0xAAAAAAAA) 1; Temp = (temp 0 2 | (temp 0xCCCCCCCC) 2; Temp = (temp 0x0F0F0F0F) 4 | (temp 0xF0F0F0F0) 4; Temp = (temp 0x00FF00FF) 8 | (temp 0xFF00FF00) 8; Temp = (temp 0x0000FFFF) 16 | (temp 0xFFFF0000) 16; Temp = temp (32 - R); Return temp; } Bool ditfft (complexdouble *TS, complexdouble *FS, int r) {// time extraction algorithm, TS sequence, FS sequence frequency, sequence length of N = 2^r Int i, J, k; Int N = 1 R //N = 2^r; Double alpha; / / phase rotation angle factor Complexdouble *W; / / rotation factor W = new complexdouble[N/2]; For (I = 0; I N/2; / / i++) to calculate the rotation factor { Alpha = -i*2*pi/N; W[i] = complexdouble (COS (alpha), sin (alpha)); } For (I = 0; I N; / / i++) time sequence inversion sequence FS[i]=TS[RevBit (I, R)]; For (I = 0; I R; i++) { Int IX = 1 (I + 1); / / the number of class I each element Int iy = 1 (R - I - 1); / / total group level I number For (J = 0; J iy; / / j++) calculation process of the butterfly { For (k = ix/2; K IX; / / k++) multiplied by the latter part of each rotation factor FS[j*ix + k = FS[+ k] j*ix]*W[(k-ix/2) *iy]; For (k = 0; K ix/2; k++) { Complexdouble TEMP1; Complexdouble TEMP2; TEMP1 FS[= j*ix + K + FS[+ K + j*ix] ix/2]; TEMP2 FS[= j*ix + K + K + j*ix - FS[]] ix/2; FS[j*ix + k = TEMP1]; FS[j*ix + K + ix/2 = TEMP2]; } } } Return true; } Bool diffft (complexdouble *TS, complexdouble *FS, int r) {// frequency extraction algorithm, TS sequence, FS sequ