function [x,n]=jacobi(A,b,eps)
if nargin==2
    eps=1e-5;
end
D=diag(diag(A));
L=-tril(A,-1);
U=-triu(A,1);
G=inv(D)*(D-A);
f=inv(D)*b;
if max(abs(eig(G)))<1
    x0=zeros(length(A),1);
    x1=G*x0+f;
    k=0;
    while norm(x1-x0,inf)>eps
        x0=x1;
        x1=G*x0+f;
        k=k+1;
    end
    x=x1;
    n=k;
else
    disp('不滿足jacobi迭代條件！');
end
end