fft的递归算法_fft(double real[], double imag[], int n) {-优快云博客

本文链接：https://blog.youkuaiyun.com/masterall/article/details/319721

博客展示了FFT递归算法的代码实现。定义了FFT类，其中calcFFT方法接收输入的实部和虚部数组，根据输入数组长度进行不同处理，当长度为1时直接赋值，否则进行递归计算，最终得到输出的实部和虚部数组。

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//fft递归算法
class FFT
{
public static void calcFFT(double[] rein,double[] imin,double[] reout,double[] imout,int N){
double[] rehe = new double[N];

double[] reho = new double[N];

double[] reHE = new double[N];

double[] reHO = new double[N];

double[] imhe = new double[N];

double[] imho = new double[N];

double[] imHE = new double[N];

double[] imHO = new double[N];

double[] Wsin = new double[N];

double[] Wcos = new double[N];

if (N==1)

  {
   reout[0]=rein[0];
   imout[0]=imin[0];

  }
  else{
   for (int i=0; i<N/2; i++)
   {
    rehe[i] = rein[2*i];

reho[i] = rein[2*i+1];

    imhe[i] = imin[2*i];
    imho[i] = imin[2*i+1];
   }

   calcFFT(rehe, imhe, reHE, imHE, N/2);
   calcFFT(reho, imho, reHO, imHO, N/2);
   for (int k=0;k<N/2;k++ )
   {
    Wsin[k]=Math.sin(2*Math.PI*k/N);
    Wcos[k]=Math.cos(2*Math.PI*k/N);
   }

   for (int k=0; k<N/2; k++)
   {
    reout[k]= reHE[k]+Wcos[k]*reHO[k]+Wsin[k]*imHO[k];
    imout[k]= imHE[k]+Wcos[k]*imHO[k]-Wsin[k]*reHO[k];
    reout[N/2+k] = reHE[k]-Wcos[k]*reHO[k]-Wsin[k]*imHO[k];
    imout[N/2+k] = imHE[k]+Wsin[k]*reHO[k]-Wcos[k]*imHO[k];
   }

}

}

}