Jacobi方法

% Jacobi方法和Gauss-Seidel方法
clear all
A = [8,-1,1;2,10,-1; 1 1 -5];
b = [1;4;3];  n = length(b);


itermax = 100; iter = 0; tol = 1e-4
x = zeros(n,1);
while iter<itermax
    iter = iter + 1;
    for i = 1: n
        xnew(i,1) = (b(i)-A(i,1:i-1)*x(1:i-1)-A(i,i+1:n)*x(i+1:n))/A(i,i);
       % xnew(i,1) = (b(i)-A(i,:)*x+A(i,i)*x(i))/A(i,i);
    end
    if norm(x - xnew)<tol
         break
    else
    x = xnew;
    end
end
iter
x