www.pudn.com > FFT_IFFT.rar > 1.cpp

#include  
#include  
#include  
#include  
#define N 1000 
/*定义复数类型*/ 
typedef struct 
{ 
	double real;//实部 
	double img;//虚部 
}complex; 
 
complex x[N], *W;  /*输入序列,变换核*/ 
int size_x=0;      /*输入序列的大小，在本程序中仅限个数为 2的次幂*/ 
double PI;         /*圆周率*/ 
 
void fft();     /*快速傅里叶变换*/ 
void ifft(); 
void initW();   /*初始化变换核*/ 
void change();  /*变址*/ 
void add(complex ,complex ,complex *); /*复数加法*/ 
void mul(complex ,complex ,complex *); /*复数乘法*/ 
void sub(complex ,complex ,complex *); /*复数减法*/ 
void divi(complex ,complex ,complex *);/*复数除法*/ 
void output(); 
 
int main() 
{ 
	int i; 
	char method;                             /*输出结果*/ 
    system("cls"); 
    PI=atan(1)*4; 
    cout<< "请输入X(n)序列的长度 :"<>size_x; 
    cout<<"请输入序列的数据"<>x[i].real; 
		cout<<"请输入虚部 :"; 
		cin>>x[i].real; 
		cout<>method; 
	if(method=='F'||method=='f') 
		fft(); 
	else 
		ifft(); 
	output(); 
	return 0; 
} 
 
/*快速傅里叶变换*/ 
void fft() 
{ 
	int i=0,j=0,k=0,l=0; 
	complex up,down,product; 
	change(); 
	for(i=0;i< log(size_x)/log(2) ;i++) 
	{                                      /*一级蝶形运算*/ 
		l=1<0 ) 
		{ 
			j=j<<1; 
			j|=(k & 1); 
			k=k>>1; 
		} 
		if(j>i) 
		{ 
			temp=x[i]; 
			x[i]=x[j]; 
			x[j]=temp; 
		} 
	} 
} 
 
/*输出傅里叶变换的结果*/ 
void output() 
{ 
	int i; 
	cout<<"The result are as follows"<=0.0001) 
			printf("+%.4fj\n",x[i].img); 
		else if(fabs(x[i].img)<0.0001)printf("\n"); 
		else printf("%.4fj\n",x[i].img); 
	} 
} 
 
void add(complex a,complex b,complex *c) 
{ 
	c->real=a.real+b.real; 
	c->img=a.img+b.img; 
} 
 
void mul(complex a,complex b,complex *c) 
{ 
	c->real=a.real*b.real - a.img*b.img; 
	c->img=a.real*b.img + a.img*b.real; 
} 
void sub(complex a,complex b,complex *c) 
{ 
	c->real=a.real-b.real; 
	c->img=a.img-b.img; 
} 
void divi(complex a,complex b,complex *c) 
{ 
	c->real=( a.real*b.real+a.img*b.img )/( b.real*b.real+b.img*b.img); 
	c->img=( a.img*b.real-a.real*b.img)/(b.real*b.real+b.img*b.img); 
}