程序.txt

此程序实现八嗲DFT运算,已调试通过! N为运算的点数,运行后再输入运算对象,然后回车即可!

#include"conio.h"
#include"math.h"
#include"stdio.h"

#define N 8
#define PI 3.1415926
#define w0 (0.125*PI)
#define Cmul(a,b,c)a.x=b.x*c.x-b.y*c.y;a.y=b.x*c.y+b.y*c.x;
#define Cequal(a,b)a.x=b.x;a.y=b.y;
#define Cadd(a,b,c)a.x=b.x+c.x;a.y=b.y+c.y;
#define Csub(a,b,c)a.x=b.x-c.x;a.y=b.y-c.y;
#define Wn(w,r)w.x=cos(2.0*PI*r/n);w.y=-sin(2.0*PI*r/n);

struct comp
{
   float x;
   float y;
 };
 
 void main()
{
  int i,j,nu2,nm1,n,m,le,le1,k,ip,z;
  int flag,f,n1;
  struct comp a[N],t,t1,w,d;
  float a_ipx,m1;
  printf("\nThis program is about FFT by DIF way.");
  printf("\nplease enter N :");
  scanf("%d",&n1);
  n=n1;
  m1=log(n1)/log(2);
  m=log(n1)/log(2);
  if(m!=m1)  n=pow(2,m+1);
  for(i=0;i<n;i++) {a[i].x=a[i].y=0.0;}
  printf("\n");
  for(i=0;i<n1;i++)
   {
     printf("\nplease enter data(%d)_[Re]:",i);
     scanf("%f",&a[i].x);
     printf("\nplease enter data(%d)_[Im]:",i);
     scanf("%f",&a[i].y);
   }
  for(z=0;z<=1;z++)
{
      flag=-1;
      for(m=(log(n)/log(2));m>=1;m--)
          {
            le=pow(2,m);
            flag++;
            le1=le/2;
            for(j=0;j<le1;j++)
                {
                 for(i=j;i<=(n-1);i+=le)
                     {
                        ip=i+le1;
                        Cequal(t,a[i]);
                        Cequal(t1,a[ip]);
                        f=(int) (i*pow(2,flag))%n;
                        Wn(w,f);
                        Cadd(a[i],t,t1);
                        Csub(a[ip],t,t1);
                        a_ipx=a[ip].x;
                        if(z==1)
                           {
                              w.y*=-1;
                           }
                        a[ip].x=a[ip].x*w.x-a[ip].y*w.y;
                        a[ip].y=a_ipx*w.y+a[ip].y*w.x;
                      }
                 }
            }
        nu2=n/2;
        nm1=n-2;
        j=0;i=0;
        while(i<=nm1)
           {
             if(i<j)
                {
                   Cequal(d,a[j]);
                   Cequal(a[j],a[i]);
                   Cequal(a[i],d);
                }
             k=nu2;
             while(k<=j)
                {
                   j=j-k;k=k/2;
                }
                 j=j+k;
                 i=i+1;
            }
        if(z==0)
            
               printf("\n The fft of the serials which input at the start is:\n\n");
       else
               printf("\n The original serials calculated by ifft is：\n\n");
                
        for(i=0;i<n;i++)
           if(z==0)
               {
                  printf("   %7.3f",a[i].x);
                  if(a[i].y>=0)
                  printf("+%7.3fj\n",a[i].y);
                  else
                  printf("-%7.3fj\n",fabs(a[i].y));
                  a[i].y=-a[i].y;
                } 
            else
               {
                 printf("   %7.3f",a[i].x/n);
                 a[i].y=-a[i].y/n;
                 if(a[i].y>=0)
                 printf("   +%7.3fj\n",a[i].y);
                 else
                 printf("   -%7.3fj\n",fabs(a[i].y));
               }
         }
             
  printf("\n");
 }