function x=seidel(A,b,x0,k)
  [n,m]=size(A)
  for i=1:n
    B(i,:)=A(i,:)/(-A(i,i))
    B(i,i)=0
    c(i)=b(i)/A(i,i)
  endfor
  c=c'
  q=norm(B,inf)
  if q<1 & n==m
    for i=1:k
      i
      x=zeros(n,1)
      x(1)=B(1,:)*x0+c(1);
      for j=2:n
        x(j)=B(j,1:j-1)*x(1:j-1)+B(j,j:n)*x0(j:n)+c(j);
      endfor
      x
      x0=x
    endfor
    else disp('the conditions are not satisfied')
  endif
endfunction