====== LaTeXサンプル ======
===== 行列 =====

<code latex>
R_\theta = 
    \begin{bmatrix}
        \cos \theta &          -  \sin \theta \\
        \sin \theta & \phantom{-} \cos \theta 
\end{bmatrix}
</code>
$$
R_\theta = \begin{bmatrix} \cos \theta & -\sin 
\theta \\ \sin \theta & \phantom{-} \cos \theta 
\end{bmatrix}
$$

===== 場合わけ =====
<code latex>
e^{-a|x|} =
\begin{cases}
    e^{ax}  & \text{if } x <    0 \\
    e^{-ax} & \text{if } x \geq 0
\end{cases}
</code>


$$
e^{-a|x|} =
\begin{cases}
    e^{ax}  & \text{if } x <    0 \\
    e^{-ax} & \text{if } x \geq 0
\end{cases}
$$

$$
\nabla \times \overrightarrow{\mathbf{B}} -
\frac{1}{C} \frac{\delta
\overrightarrow{\mathbf{E}}}{\delta t} = 4\pi
\rho
$$

$$
{\cal H}=\mathcal{H}
$$