FFT.rar_fft_数字信号 fft

#include <math.h> #include <iostream.h> #define M 4 #define pi 3.141592653 //#define fs 8000 struct compx{float real,imag;}; struct compx EE(struct compx,struct compx); struct compx EE(struct compx a,struct compx b) { struct compx c; c.real=a.real*b.real-a.imag*b.imag; c.imag=a.real*b.imag+a.imag*b.real; return c; } void FFT(struct compx *xin, int N) { int f,m,nm1,i,k,j=1,I; struct compx v,w,t; f=N; for(m=1;(f=f/2)!=1;m++) {;} nm1=N-1; for(i=1;i<=nm1;i++) { if(i<j) { t=xin[j];xin[j]=xin[i];xin[i]=t; } k=N/2; while(k<j) {j=j-k;k=k/2;} j=j+k; } { int le,lei,ip; for(I=1;I<=m;I++) { le=int(pow(2,I)); lei=le/2; v.real=1.0; v.imag=0.0; w.real=float(cos(pi/lei)); w.imag=float(-sin(pi/lei)); for(j=1;j<=lei;j++) { for(i=j;i<=N;i=i+le) { ip=i+lei; t=EE(xin[ip],v); xin[ip].real=xin[i].real-t.real; xin[ip].imag=xin[i].imag-t.imag; xin[i].real=xin[i].real+t.real; xin[i].imag=xin[i].imag+t.imag; } v=EE(v,w); } } } } void main() { struct compx x[M+1]; cout<<"The input array is:\n"; for(int i=1;i<=M;i++) { //x[i].real=float(cos(2*pi*i*3500/fs)); x[i].real=float(i); x[i].imag=0; cout<<x[i].real<<"+j*"<<x[i].imag<<"\n"<<endl; } struct compx *p=x; FFT(p+1,M); cout<<"The result of FFT:\n"; for(i=1;i<=M;i++) cout<<x[i].real<<"+j*"<<x[i].imag<<"\n"<<endl; }