L=\left [\begin{array}{cccc} 1 & 0 & 0 & 0 \\ l_1 & 1 & 0 & 0 \\ l_2 & l_3 & 1 & 0 \\ l_4 & l_5 & l_6 & 1 \end{array} \right ] \quad U=\left [\begin{array}{cccc} u_1 & u_2 & u_3 & u_4 \\ 0 & u_5 & u_6 & u_7 \\ 0 & 0 & u_8 & u_9 \\ 0 & 0 & 0 & u_{10} \end{array} \right ],