其实之前整过这一类，但是好像在本地没有存档，这边就重新记录一下

绘制花括号函数

{\begin{equation} \left\{ \right. \end{equation}

{x=3/pi2(1+2t)cos(3/pi2(1+2t)),y=s,0≤s≤L,∣t∣≤1.z=3/pi2(1+2t)sin(3/pi2(1+2t)),\begin{equation} \left\{ \begin{array}{lr} x=\frac{3/pi}{2}(1+2t)cos(\frac{3/pi}{2}(1+2t)),\\ y=s, & 0\le s \le L, |t|\le 1.\\ z=\frac{3/pi}{2}(1+2t)sin(\frac{3/pi}{2}(1+2t)), \end{array} \right. \end{equation}

分段函数

y={x−1,x≤0x+1,x>0y= \begin{equation} \left\{ \begin{array}{c} x-1,& x \le 0\\ x+1, & x>0 \end{array} \right. \end{equation}

Fnij={Pij∗Fn1 orRij∗Fn2 orSij∗Fn2F_{nij}=\begin{equation} \left\{ \begin{array}{c} P_{ij}*F_{n1} \ or\\ R_{ij}*F_{n2} \ or\\ S_{ij}*F_{n2} \end{array} \right. \end{equation}