在CSDN-Markdown中书写多行大括号公式

方法一：

$$ f(x)=\left\{
\begin{aligned}
x & = & \cos(t) \\
y & = & \sin(t) \\
z & = & \frac xy
\end{aligned}
\right.
$$

方法二：
$$ F^{HLLC}=\left\{
\begin{array}{rcl}
F_L       &      & {0      <      S_L}\\
F^*_L     &      & {S_L \leq 0 < S_M}\\
F^*_R     &      & {S_M \leq 0 < S_R}\\
F_R       &      & {S_R \leq 0}
\end{array} \right. $$

方法三:
$$f(x)=
\begin{cases}
0& \text{x=0}\\
1& \text{x!=0}
\end{cases}$$

方法一：

$$f(x)=\{\begin{array}{rlr}x& =& \cos (t)\\ y& =& \sin (t)\\ z& =& \frac{x}{y}\end{array}$$

方法二：
$$F^{HLLC}=\{\begin{array}{rcl}{F}_L& & 0<S_L\\ F_L^{\ast }& & S_L\le 0<S_M\\ F_R^{\ast }& & S_M\le 0<S_R\\ F_R& & S_R\le 0\end{array}$$

方法三:
$$f(x)=\{\begin{array}{ll}0& \text{x=0}\\ 1& \text{x!=0}\end{array}$$