1、 1 / 4FFT 算法实验1.FFT 算法的 C 语言实现程序/*FFT*/#include #include #include #define N 1000typedef structdouble real;double img;complex;void fft(); /*快速傅里叶变换*/void ifft(); /*快速傅里叶逆变换*/void initW();void change();void add(complex ,complex ,complex *); /*复数加法*/void mul(complex ,complex ,complex *); /*复数乘法*/void s
2、ub(complex ,complex ,complex *); /*复数减法*/void divi(complex ,complex ,complex *);/*复数除法*/void output(); /*输出结果*/complex xN, *W;/*输出序列的值*/int size_x=0;/*输入序列的长度，只限 2的 N次方*/double PI;int main()int i,method;system(“cls“);PI=atan(1)*4;printf(“Please input the size of x:n“);/*输入序列的长度*/scanf(“%d“,printf(“P
3、lease input the data in xN:(such as:5 6)n“);/*输入序列对应的值*/for(i=0;isize_x;i+)scanf(“%lf %lf“,initW(); /*选择 FFT或逆 FFT运算*/printf(“Use FFT(0) or IFFT(1)?n“);scanf(“%d“,if(method=0)2 / 4fft(); else ifft(); output();return 0; /*进行基-2 FFT 运算*/void fft()int i=0,j=0,k=0,l=0;complex up,down,product; change();f
4、or(i=0;i log(size_x)/log(2) ;i+) l=1i; for(j=0;jsize_x;j+= 2*l ) for(k=0;kl;k+) mul(xj+k+l,Wsize_x*k/2/l, add(xj+k,product, sub(xj+k,product,xj+k=up; xj+k+l=down;void ifft()int i=0,j=0,k=0,l=size_x;complex up,down; for(i=0;i (int)( log(size_x)/log(2) );i+) /*蝶形运算*/l/=2;for(j=0;jsize_x;j+= 2*l )for(k
5、=0;kl;k+)add(xj+k,xj+k+l,up.real/=2;up.img/=2;sub(xj+k,xj+k+l,down.real/=2;down.img/=2;divi(down,Wsize_x*k/2/l,3 / 4xj+k=up; xj+k+l=down; change(); void initW() int i;W=(complex *)malloc(sizeof(complex) * size_x); 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() complex temp;unsigned short i=0,j=0,k=0; double t;for(i=0;isize_x;i+) k=i;j=0;2.AD 端口原理图图 1 TMS320F28335硬件图4 / 4图 2 ADC硬件连接图
