C++实现FFT算法

C++实现FFT算法

#include "iostream.h"
#include "stdio.h"
#include "math.h"
#include "stdlib.h"
#include "malloc.h"
#define PI (float)3.1415926//复数结构体
typedef struct{ float re; float im;}complex;//定义旋转因子
complex W(int N,int n){
 complex out; out.re=(float)cos(2*PI*((float)n/(float)N));
 out.im=-(float)sin(2*PI*((float)n/(float)N)); return out;
}
//复数加法，out=a+b
complex add(complex a,complex b){
 complex out;
 out.re=a.re+b.re;
 out.im=a.im+b.im;
 return out;}
//复数减法，out=a-b
complex sub(complex a,complex b){
 complex out;
 out.re=a.re-b.re;
 out.im=a.im-b.im;
 return out;}
//复数乘法，out=a*b
complex mul(complex a,complex b){
 complex out;
 out.re=a.re*b.re-a.im*b.im;
 out.im=a.re*b.im+a.im*b.re;
 return out;
}
//复数赋值
complex comcpy(complex a){
 complex out;
 out.re=a.re;
 out.im=a.im;
 return out;
}

bool DOFFT(complex *x,complex *F,int N){
 int K=(int)(log(N+1)/log(2));// cout< int i,j,m; for(m=1;m<=K;m++) {//  cout<<"m="<  for(i=0;i<(1<   for(j=0;j<(1<<(m-1));j++){//    cout<    F[i+j]=add(x[i+j],mul(x[i+j+(1<<(m-1))],W(1<    F[i+j+(1<<(m-1))]=sub(x[i+j],mul(x[i+j+(1<<(m-1))],W(1<   } //   cout<<"\t"; 
  }
  //  cout<   for(i=0;i    x[i]=comcpy(F[i]);
  }
  return true;
}

int reverse(int n,int j){

  int  i,k,power;
  power=(int)(log(n+1)/log(2));
  k=0;
  for(i=0;i   if(j&(1<    k+=1<<(power-i-1);//如果正序数中位i的值为1，则倒序数中power-i-1的相应位置1。
  return k;

}

void main(){

  int m,i,j;
  int N=4;
  complex *x,*F;
  x=new complex[N];
  F=new complex[N];
  for(i=0;i   x[i].re=1;
   x[i].im=0;
   cout<<"x["<  }
  for(i=N/2;i   x[i].re=0;
   x[i].im=0;
   cout<<"x["<  }
  cout<

  for(i=0;i   F[i]=comcpy(x[reverse(N,i)]);
  }
  for(i=0;i   x[i]=comcpy(F[i]);
  }
  for(i=0;i   cout<<"x["<  }

  cout<

  DOFFT(x,F,N);
  for(i=0;i  { 
   cout<<"("<  }

  cout<

}

转载于:https://www.cnblogs.com/MMLoveMeMM/articles/3064005.html