澳洲计算机IT 编程assignment 代写

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#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <float.h>
#include <malloc.h>
#include "q2_header.h"
 
void DFT(double *x, double *y,int N)
{
         double **CNI;
         CNI=makeCNI(N);
         complexMatrixVectorMultiply(CNI,y,N,N,x);
}
void FastDFT(double *x,double *y,double *w,double *Wp,int N,int skip);

void FastDFT(double *x,double *y,double *w,double *Wp,int N,int skip)
{
    int i,j;
    if (N==1)
    {
             memcpy(x,y,2*sizeof(double));
    }
    else if (N % 2 && N!=1)
    {
        DFT(x,y,N);
    }
    else
    {
             /*place xe and xo in w,from head to tail.*/
        for (i=0;i<N;i=i+2)
        {
                 memcpy(w+i,x+2*i,2*sizeof(double));
        }
 
        for (i=0;i<N;i=i+2)
        {
                 memcpy(w+(i+N),x+(2*i+2),2*sizeof(double));
        }
 
        FastDFT(w,y,x,Wp,N/2,skip*2);//the even half of y, i.e., ye
        FastDFT(w+N,y+N,x+N,Wp,N/2,skip*2);//the odd half of y, i.e., yo
 
        memcpy(w,y,sizeof(double)*2*N);//copy the value of ye,yo into w.
        for(j=0;j<N;j+=2)
        {
                 double temp[2]={0,0};
                 double times[2]={N,0};
                 complexMultiply(&Wp[2*N-j],&w[j+N],&temp);
                 complexMultiply(&temp,&times,&temp);
                 complexAdd(&w[j],&temp,&y[j]);
                 complexMultiply(&Wp[N-j],&w[j+N],&temp);
                 complexMultiply(&temp,&times,&temp);
                 complexAdd(&w[j],&temp,&y[j+N]);
        }
    }
}