FFT得C語言算法實現(xiàn)

1、FFT得C語言算法實現(xiàn)程序如下:/*FFT*/#include#include#include#defineN 1000typedefstructdoublereal;doubleimg;plex;voidvoidinitW();voidchange();voidadd(plex,plex,plex*); /*復(fù)數(shù)加法*/voidmul(plex,plex,plex*); /*復(fù)數(shù)乘法*/voidsub(plex,plex,plex*); /*復(fù)數(shù)減法*/voiddivi(plex,plex,plex*);/*復(fù)數(shù)除法*/voidoutput(); /*輸出結(jié)果*/plexxN, *W;/*輸

2、出序列得值*/int main()void*/fft(); /*快速傅里葉變換*/ ifft(); /*快速傅里葉逆變換/*選擇FFT或逆FFT運算*/printf(Use FFT(0) or IFFT(1)?n);scanf(%d,&method);if(method=0) fft();elseifft();output();return 0;/*進(jìn)行基-2 FFT運算*/ void fft()int i,method;system(cls);PI=atan(1)*4;printf(Please input /*輸入序列得長度*/scanf(%d,&size_x);print

3、f(Please input6)n);/*輸入序列對應(yīng)得值*/for(i=0;isize_x;i+)scanf(%lf %lf,&xi、initW();the size of x:n);the data in xN:(such as:5real,&xi、img);int i=0,j=0,k=0,l=0;plex up,down,product;change();for(i=0;i log(size_x)/log(2)l=1i;for(j=0;jsize_x;j+=for(k=0;kl;k+)mul(xj+k+l,Wsize_x*k/2/l,&product);add(x

4、j+k,product,&up);sub(xj+k,product,&down);xj+k=up;xj+k+l=down;voidintplex;i+)2*lifft()i=0,j=0,k=0,l=size_x; up,down;(int)( log(size_x)/log(2) );i+) /*蝶形運算for(i=0;i*/l/=2; for(j=0;jsize_x;j+=for(k=0;kl;k+)add(xj+k,xj+k+l,&up); up、real/=2;up、img/=2;sub(xj+k,xj+k+l,&down); down、real/=2;d

5、own、img/=2;divi(down,Wsize_x*k/2/l,&down); xj+k=up;xj+k+l=down; change();void initW()int i;W=(plex *)malloc(sizeof(plex)for(i=0;isize_x;i+)Wi、real=cos(2*PI/size_x*i); Wi、img=-1*sin(2*PI/size_x*i);void change()plex temp;unsigned short i=0,j=0,k=0; double t;for(i=0;i0 )j=j1;2*lsize_x);if(ji)temp=x

6、i; xi=xj;xj=temp;void output() /*輸出結(jié)果*/c-real=a、real-b、real;int i;printf(The result are as followsn);for(i=0;i=0、0001) printf(+%、4fjn,xi、img); elseif(fabs(xi、img)real=a、real+b、c-img=a、img+b、void mul(plexreal;img;a,plexb,plex *c)c-real=a、real*b、c-img=a、real*b、void sub(plexrealimga,plexa、img*b、img;a、img*b、real;b,plex *c)0001)a,plexb,plex *c)c-img=a、img-b、img;void divi(plex a,plex b,plex *c)c-real=( real+b、img*b、img);