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\begin{document}
    \Large
    % \begin{eqnarray*}
    %   & &
    %   \DP{\phi}{t}  = \kappa \Dlapla \phi, \quad
    %   % \phi = 0 \ \mbox{at} \ r=r_{in},r_{out}, 
    %   % \DP{\phi}{r} = 0 \ \mbox{at} \ r=r_{in},r_{out}, 
    %   % \DP{\phi}{r} = 0 \ \mbox{at} \ r=r_{out}, \quad
    %   %   \phi = 0 \ \mbox{at} \ r=r_{in}, 
    %   % \phi = 0 \ \mbox{at} \ r=r_{out}, \quad
    %   %   \DP{\phi}{r} = 0 \ \mbox{at} \ r=r_{in}, 
    %   \\ & &
    %   \left.\DD{\tilde{\phi}_{l}}{r}\right|_{r_{out}}
    %           +\frac{(l+1)}{r_{oot}}\tilde{\phi}_{l}|_{r_{out}}=0, \quad
    %   \left.\DD{\tilde{\phi}_{l}}{r}\right|_{r_{in}}
    %           -\frac{l}{r_{in}}\tilde{\phi}_{l}|_{r_{in}}=0.
    %   \\
    %   & & \qquad
    %   \tilde{\phi}_l(r,t) = \int_{-\pi/2}^{\pi/2} \phi(r,\varphi,t)Y_l^0(\varphi) \cos\varphi d\varphi, 
    %   \\
    %   & & \qquad
    %   \Dlapla = \frac{1}{r^2}\DP{}{r}\left(r^2\DP{}{r}\right)
    %                 + \frac{1}{r^2\cos\varphi}\DP{}{\varphi}
    %                    \left(\cos\varphi\DP{}{\varphi}\right),
    %             \quad \kappa \mbox{: const.}
    % \end{eqnarray*}

    % �ȥ�������Ȼ�����
    % \begin{eqnarray*}
    %   & &
    %   \DP{\phi}{t}  = \kappa \Dlapla \phi, \quad
    %   % \DP{}{r}\left(\frac{\phi}{r}\right) = 0 \ \mbox{at} \ r=r_{out}, \quad
    %   %   \phi = 0 \ \mbox{at} \ r=r_{in}, \\
    %   % \phi = 0 \ \mbox{at} \ r=r_{out}, \quad
    %   %   \DP{}{r}\left(\frac{\phi}{r}\right) = 0 \ \mbox{at} \ r=r_{in}, \\
    %   \DP{}{r}\left(\frac{\phi}{r}\right) = 0 \ \mbox{at} \ r=r_{in},r_{out}, \\
    %   & & \qquad
    %   \Dlapla = \frac{1}{r^2}\DP{}{r}\left(r^2\DP{}{r}\right)
    %                 + \frac{1}{r^2\cos\varphi}\DP{}{\varphi}
    %                    \left(\cos\varphi\DP{}{\varphi}\right),
    %             \quad \kappa \mbox{: const.}
    % \end{eqnarray*}
    
    % �ݥ�������Ȼ�����
    \begin{eqnarray*}
      & &
      \DP{}{t} (\Dlapla \phi) = \nu \Dlapla\Dlapla \phi, \quad
      \phi = \DP{\phi}{r} = 0 \ \mbox{at} \ r=r_{in},r_{out}, \\
      & & \qquad
      \Dlapla = \frac{1}{r^2}\DP{}{r}\left(r^2\DP{}{r}\right)
                    + \frac{1}{r^2\cos\varphi}\DP{}{\varphi}
                       \left(\cos\varphi\DP{}{\varphi}\right),
                \quad \nu \mbox{: const.}
    \end{eqnarray*}
 
\end{document}

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