<n, n> = size(A); 
X = eye(n);
anorm = norm(A,'fro');
cnt = 1;
while cnt > 0,...
  cnt = 0;...
  for p = 1:n-1,...
    for q = p+1:n,...
      if anorm + abs(a(p,q)) > anorm,...
        cnt = cnt + 1;...
        exec('jacstep');...
      end,...
    end,...
  end,...
  display(rat(A)),...
end
