fft快速傅里叶变换-c语言实现.doc

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1、#include#include#include#defineN1000/*定义复数类型*/typedefstruct{doublereal;doubleimg;}complex;complexx[N],*W;/*输入序列,变换核*/intsize_x=0;/*输入序列的大小，在本程序中仅限2的次幂*/doublePI;/*圆周率*/voidfft();/*快速傅里叶变换*/voidinitW();/*初始化变换核*/voidchange();/*变址*

2、/voidadd(complex,complex,complex*);/*复数加法*/voidmul(complex,complex,complex*);/*复数乘法*/voidsub(complex,complex,complex*);/*复数减法*/voidoutput();intmain(){inti;/*输出结果*/system("cls");PI=atan(1)*4;printf("Pleaseinputthesizeofx:");scanf("%d",&size_x);printf("Ple

3、aseinputthedatainx[N]:");for(i=0;i

4、;j+=2*l){/*一组蝶形运算*/for(k=0;k

5、[i].real=cos(2*PI/size_x*i);W[i].img=-1*sin(2*PI/size_x*i);}}/*变址计算，将x(n)码位倒置*/voidchange(){complextemp;unsignedshorti=0,j=0,k=0;doublet;for(i=0;i0){j=j<<1;j

6、=(k&1);k=k>>1;}if(j>i){temp=x[i];x[i]=x[j]

7、;x[j]=temp;}}}/*输出傅里叶变换的结果*/voidoutput(){inti;printf("Theresultareasfollows");for(i=0;i=0.0001)printf("+%.4fj",x[i].img);elseif(fabs(x[i].img)<0.0001)printf("");elseprintf("%.4fj",x[i].img);}}voidad

8、d(complexa,complexb,complex*c){c->real=a.real+b.real;c->img=a.img+b.img;}voidmul(complexa,complexb,complex*c){c->real=a.real*b.real-a.img*b.img;c->img=a.real*b.img+a.img*b.real;}voidsub(complexa,complexb,complex*c){c->real=a.real-b.real;c->img=a.img-b.img;

9、}