[vox-tech] latex help

[Peter Jay Salzman]

solved.  it's a total hack, but looks pretty good:


Consider the $k$'th component:

\begin{equation*}
\begin{matrix}
\left( \vp \times \vA \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( \vp \times \vA \right)_k = A_i p_j - A_j p_i & \\[8pt]
%
\noalign{\hrule}\\[-5pt]
%
\end{matrix}
\end{equation*}

\begin{equation*}
	\text{Sum} = -i\hbar \left[ \fpar{}{x_i}A_j  - \fpar{}{x_j}A_i \right]
	= -i\hbar \left[ \vn \times \vA \right]_k
\end{equation*}


p


begin Peter Jay Salzman <p@dirac.org> 
> 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
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