[texhax] Typesetting row operations in matrices

[E. Krishnan]

On Fri, 24 Mar 2006, Matthew Leingang wrote:

> When I'm talking at the board and I want to say "we're going to transpose
> row 1 and row 3 of this matrix", I draw a double-ended arrow on the
> right-hand side of the matrix, pointing to the first and third row.  If I
> want to represent the row operation "add -2 times the first row to the
> second row", I draw an arrow from the right side of row 1 to the right side
> of row 2, decorated with a "-2".
> 
> I'd like to get the same thing in my TeX-ed notes.  


Please have a look at this:

  \documentclass{article}
  \usepackage{amsmath}
  \usepackage{pstricks,pst-node}

  \begin{document}

  \begin{equation*}
    \psset{nodesep=5pt,%
           linestyle=dotted,%
           dotsep=1pt}
    \begin{pmatrix}  
      1 & 2 & \rnode{1}{3}\\
      4 & 5 & 6\\
      7 & 8 & \rnode{3}{9}
    \end{pmatrix}
    \ncbar{<->}{1}{3}
    \Aput[1pt]{\scriptstyle{-2}}
  \end{equation*}

\end{document}


-- 
Krishnan