function[C,B,A]=dir2fs(h)  %直接型到頻率采樣型轉(zhuǎn)換
M=length(h)
H=fft(h,M);
magH=abs(H);phaH=angle(H)';
if(M==2*floor(M/2))
   L=M/2-1;
   A1=[1,-1,0;1,1,0];
   C1=[real(H(1)),real(H(L+2))];
else
   L=(M-1)/2;
   A1=[1,-1,0];
   C1=[real(H(1))];
end
k=[1:L]';
B=zeros(L,2);A=ones(L,3);
A(1:L,2)=-2*cos(2*pi*k/M);A=[A;A1];
B(1:L,1)=cos(phaH(2:L+1));
B(1:L,2)=-cos(phaH(2:L+1)-(2*pi*k/M));
C=[2*magH(2:L+1),C1]';