function normx = normalize(x,a,b,min0,max0)
    normx = zeros(size(x));
    xmax = max(x(:));
    xmin = min(x(:));
    if nargin > 3
        % norm x with same ration of [min0, max0] -> [a,b]
        a1 = a*xmin/min0;
        b1 = b*xmax/max0;
        k = (b1-a1)/(xmax-xmin);
        normx(:) = a1 + k*(x(:)-xmin); 
    else
        k = (b-a)/(xmax-xmin);
        normx(:) = a + k*(x(:)-xmin);    
    end
end