Latex 多行公式等号对齐

无编号

\begin{align*}
  p(f_1=0) &= 0.8/0.9*p(s_1=0)+0.1/0.9*p(s_2=0) \\
 &= 0.8/0.9*0.4+0.1/0.9*0.6  \\
 &= 0.4222
\end{align*}

[img]http://dl2.iteye.com/upload/attachment/0107/6665/4ea9af03-4258-3423-afa8-0044bf1dd791.jpg[/img]


有编号

\begin{align}
          & &-e^{-\Phi} \Phi'(a^3 \Phi v) + e^{-\Phi} \Phi_z(a^3 \Phi v) &= a^5 e^{-\Phi}m_X^2 v + a^5 e^{-\Phi} \frac{\lambda}{2}v^3 \nonumber \\
\Longrightarrow & &- \Phi'(a^3 \Phi v) +  \Phi_z(a^3 \Phi v) &= a^5 m_X^2 v + a^5 \frac{\lambda}{2}v^3 \nonumber  \\
\Longrightarrow & &a^3 v'(- \Phi') + (a^3 v')' &= a^5 (m_X^2 v + \frac{\lambda}{2}v^3)  \\ \label{phi'1}
\Longrightarrow & &a^3 v' - a^5 ( m_X^2 v + \frac{\lambda}{2} v^3 ) &= a^3 v' \Phi'\nonumber 
\end{align}

[img]http://dl2.iteye.com/upload/attachment/0107/6667/e272be37-a51f-3a88-b53c-520da4d01e45.jpg[/img]