\listfiles
\documentclass{jarticle}
\usepackage{amsmath}
\usepackage{dotseqn}

\begin{document}

数式と数式番号の間をドットで埋める。

\begin{align}
f(x)&=false \\
f(x)&=false
\end{align}


\begin{equation}
|x|=
\begin{cases}
   x, & \text{for $x \geq 0$ }\\
 -x, & \text{for $x < 0$}
\end{cases}  
\end{equation}

\begin{equation}
 \left.
 \begin{array}{r}
  y=f(x) \\
  z=g(y)
 \end{array}
 \right\} \qquad z=g\circ f(x)
\end{equation}

\begin{eqnarray}
&&\nabla \times \overrightarrow{F}  \notag \\ 
& =&  \left|
   \begin{array}{ccc}
     \widehat{i} & \widehat{j} & \widehat{k} \\
     \frac {\partial }{\partial x} & \frac {\partial }{\partial y} &\frac{\partial }{\partial z} \\
     F_x & F_y & F_z  
   \end{array} 
   \right|
 \\
& =&  \left( \frac {\partial F_z}{\partial y} 
 - \frac {\partial F_y} {\partial z} \right) \widehat{i}
 + \left( \frac{\partial F_x} {\partial z}
 -\frac {\partial F_z} {\partial x} \right) \widehat{j}
 +\left( \frac {\partial F_y} {\partial x} 
 - \frac {\partial F_x} {\partial y} \right) \widehat{k}
\end{eqnarray}

\end{document}
