谐波分析源程序

1、 #include #include #include #define N 256#define dt 0. /采样间隔0.ms#define t_min 0 /一个周期采样时间下限#define t_max 20 /一个周期采样时间上限#define PI 3. /圆周率#define size_x 256 /输入序列XN的大小，在本程序中仅限2的次幂typedef struct /定义复数类型double real;double img;complex;complex xN, *W; /xN:FFT输入序列,*W:FFT变换核 int U_t(double t) /返回每个t ms对应的U

2、值t=t-(long)(t)/20*20;if(t=4&t=14&treal=a.real+b.real;c-img=a.img+b.img;void mul(complex a,complex b,complex *c) /复数乘法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) /复数减法c-real=a.real-b.real;c-img=a.img-b.img;void change() /变址计算，将x(n)码位倒置

3、complex temp;unsigned short i=0,j=0,k=0;double t;for(i=0;i0 ) j=j1; if(ji) temp=xi;xi=xj;xj=temp; void initW() /初始化变换核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 fft() /快速傅里叶变换int i=0,j=0,k=0,l=0;complex up,down,

4、product;change();for(i=0;i log(size_x)/log(2) ;i+) /*一级蝶形运算*/l=1i;for(j=0;jsize_x;j+= 2*l ) /*一组蝶形运算*/for(k=0;kl;k+) /*一个蝶形运算*/mul(xj+k+l,Wsize_x*k/2/l,&product);add(xj+k,product,&up);sub(xj+k,product,&down);xj+k=up;xj+k+l=down;int main()double t,sum=0,square_sum=0,average,effective; /t:时间，average：平

5、均值，effective：有效值long count=0;for(t=t_min;tt_max;t=t+dt)count+;sum+=U_t(t);square_sum+=U_t(t)*U_t(t);average=sum/count;effective=sqrt(square_sum/count);printf(平均值：%f，有效值：%fn*n*谐波有效值*n*n,average,effective);for(t=t_min,count=0;countsize_x;t=t+dt,count+)xcount.real=U_t(t);xcount.img=0;initW();fft();for(count=1;count=15;count+)