function [aa]=lpc_zj(x,p)
m=p;
k=length(x);
for i=1:21
r(i)=0;
kk(i)=0;
e(i)=0;
end
for i=1:21
for j=1:21
a(i,j)=0;
end
end
for j=1:(m+1)
for i=1:(k-j)
r(j)=r(j)+x(i)*x(j+i-1);
end
end
e(1)=r(1);
a(1,1)=r(2)/r(1);
kk(1)=r(2)/e(1);
e(2)=(1-kk(1)*kk(1))*e(1);
for i=2:m
sum=0;
for j=1:i-1
sum=sum+a(i-1,j)*r(i-j+1);
end
kk(i)=(r(i+1)-sum)/e(i);
a(i,i)=kk(i);
for j=1:i-1
a(i,j)=a(i-1,j)-kk(i)*a(i-1,i-j);
end
e(i+1)=(1-kk(i)*kk(i))*e(i);
end
for j=1:m
aa(j)=-a(m,j);
end
