测试公式

$f(x_1) = sin(x_1)^2$

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

$$
sum_{i=0}^Nint_{a}^{b}g(t,i)text{d}t
$$

$$begin{bmatrix}
{a_{11}}&{a_{12}}&{cdots}&{a_{1n}}\
{a_{21}}&{a_{22}}&{cdots}&{a_{2n}}\
{vdots}&{vdots}&{ddots}&{vdots}\
{a_{m1}}&{a_{m2}}&{cdots}&{a_{mn}}\
end{bmatrix}$$

$$begin{cases}
a_1x+b_1y+c_1z=d_1\
a_2x+b_2y+c_2z=d_2\
a_3x+b_3y+c_3z=d_3\
end{cases}
$$