# [texhax] Typesetting row operations in matrices

Matthew Leingang leingang at math.harvard.edu
Tue Apr 4 20:49:04 CEST 2006

Thanks to all who responded.  I even got some tips on the Xy-pic side from
Ross Moore.  But I think I'll go with gauss.sty.  It does everything I need
except for curved arrows, and I don't think I need that.

That reminds me of Pete's Pretty Good Grocery, a frequent sponsor of the
radio show A Prairie Home Companion.  Their slogan is, "If we don't have it,
you can probably live without it."

On 3/24/06 10:18 PM, "E. Krishnan" <ekmath at asianetindia.com> wrote:

> 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}
>

--
Matthew Leingang
Preceptor in Mathematics
Harvard University

URL: http://www.math.harvard.edu/~leingang/
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