五点校正算法：精确频率、幅值和相位提取

N=256; fs=1000; f=51.1234; a=1.2345; ph=30.123; dc=0.123; t=0:N-1; x=asin(2pift/fs+phpi/180)+dc; xfft=fft(x,N); y=abs(xfft); [Y1, k]=max(y(2:N/2)); k=k+1; z1=xfft(k)-(xfft(k-1)+xfft(k+1))/2; z2=xfft(k+1)-(xfft(k)+xfft(k+2))/2; ka=abs(z1)/abs(z2); r=(2-ka)/(1+ka); fo=(k-1+r)fs/N; ao=2pir*(1-rr)(abs(z1))/(Nsin(rpi)); pho=(angle(z1)-pi*r)*180/pi+90;