r2fft.cpp

信号处理的几种算法

   
 void fft(double x[64],double y[64],int n,int sign);
 void r2fft(double x[64],double y[64],int n)
 {
	 int i,n1;
	 double tr,ti;
	 n1=n/2;
	 fft(x,y,n,1);
	 for(i=1;i<n1;i++)
	 {
		 tr=(x[i]+x[n-i])/2;
		 ti=(y[i]-y[n-i])/2;
		 y[i]=(y[n-i]+y[i])/2;
		 y[n-i]=(x[n-i]-x[i])/2;
		 x[i]=tr;
		 x[n-i]=ti;
	 }
 }