[vox-tech] latex help

[Peter Jay Salzman]

hey there,

i'm trying to achieve this effect in latex (i'm adding two equations
together):


      a  =  b + f
      d  =  e + f
     ---------------
     a+d = b + e +f

here's what i have:

\begin{align*}
\left( \vec{p} \times \vec{A} \right)_k =& p_i A_j - p_j A_i = -i\hbar
  \fpar{A_j}{x_i} + A_j p_i - \left[ -i\hbar \fpar{A_i}{x_j} - A_i p_j \right]\\
\left( \vec{p} \times \vec{A} \right)_k =& A_i p_j - A_j p_i \\[5pt]
%
\noalign{\hrule}\\[-5pt]
%
\text{Sum} =& -i\hbar \left[ \fpar{}{x_i}A_j - \fpar{}{x_j}A_i \right]
= -i\hbar \left[ \vec{\nabla}\times \vec{A} \right]_k
\end{align*}

it almost works.  here's what i'm getting:


      a  =  b + f
      d  =  e + f
--------------------
     a+d = b + e +f

the hrule goes to the left margin.  i've tried playing around with
parboxes to no avail.


anyone know how to do this?

pete