%--------------------------
 % @Author: Jingqiao Hu
 % @Date: 2020-10-30 19:13:57
 % @LastEditors: Jingqiao Hu
 % @LastEditTime: 2020-11-10 21:01:00
%--------------------------
% fast_version
function P = PK1_fast(u, l, F)
    Fdet = F(1, :).*F(4, :) - F(2, :).*F(3, :);
    % if sum(Fdet<0)>0
    %     2333;
    % end
    JJ   = log(Fdet);
    Finv = F([4,2,3,1], :) .* [1;-1;-1; 1] ./ Fdet;
    FinvT = Finv([1,3,2,4], :);

    P = u(:)' .* (F - FinvT) + l(:)' .* JJ .* FinvT;
end