生成数学公式
$\sum_{i=0}^N\int_{a}^{b}g(t,i)\text{d}t$
\[F^{HLLC}=\left\{ \begin{array}{rcl} F_L & & {0 < S_L}\\ F^*_L & & {S_L \leq 0 < S_M}\\ F^*_R & & {S_M \leq 0 < S_R}\\ F_R & & {S_R \leq 0} \end{array} \right.\] \[\begin{matrix} 1&0&0\\ 0&1&0\\ 0&0&1\\ \end{matrix}\]