function [x,k,index]=Jacobi(a,b,ep,it_max)
if nargin<4 it_max=100;end
if nargin<3 ep=1e-5; end
n=length(a);k=0;
x=zeros(n,1);y=zeros(n,1);index=1;
while 1
    for i=1:n
        y(i)=b(i);
        for j=1:n
            if j~=i
                y(i)=y(i)-a(i,j)*x(j);
            end
        end
        if abs(a(i,i))<1e-15 | k==it_max
            index=0;return;
        end
        y(i)=y(i)/a(i,i);
    end
    if norm(y-x,inf)<ep
        break;
    end
    x=y;k=k+1;
end