# [OS X TeX] xy-pic problems

Roger Hart rhart at mail.utexas.edu
Sat Oct 30 01:47:03 CEST 2004

I've been trying to use xy-pic to draw some diagrams and have had two
major troubles which I've been unable to solve: 1) the arrows it draws
are jagged, very noticeably so in printouts; 2) resizing does not work
properly, resulting in arrows missing their intended targets.

Specifically, I just want to draw a diagram showing the order of the
multiplication of entries in a 3x3 determinant, so I wrote:

$\xymatrix { a_{11} \ar@{->}'[dr][ddrr] & a_{12} \ar@{->}'[dr][ddrr] & a_{13} \ar@{->}'[dr][ddrr] & a_{11} & a_{12} \\ a_{21} & a_{22} & a_{23} & a_{21} \\ a_{31} \ar@{->}'[ur][uurr] & a_{32} \ar@{->}'[ur][uurr] & a_{33} \ar@{->}'[ur][uurr] & a_{31} & a_{32} \\ }$

I also want to show the order of multiplication in an ancient Chinese
mathematical treatise,

$\fbox{ \xymatrix { &&&&&&&\\ &| & & & & || & \\ & & & & ||| ~ & | & \\ & & & |||| \ar[dl]_{(i)~4-1=3} & | & & \\ & & ||||| \ar[dl]_{(ii)~(3 \times 5) + 1 = 16} & | & & & \\ & \overline{~|~} \ar dl^r[0,5]_-{(iii)~(16 \times 6) - 1 = 95} ^u[0,5] ^u[0,5] ^dl[-4,4] [-4,4]_{(iv)~(95 \times 2) + 1 = 191} & | & & & &\\ &&&&&& &\\ } }$

Unfortunately, the arrows are jagged.  And because xy-pic is designed
more for commutative diagrams than the matrices I wish to draw, I need
to reduce their size, and I've tried all sorts of arguments and values
to try to get the arrows to look nice, such as,

@! @R=6pt @C=6pt @M=0pt @H=0pt @W=0pt

but have been unable to get straight arrows at any size.  And when I
use various parameters above, the arrows fail to connect to their
targets.

I'm not sure what I'm doing wrong, and obviously, I'm not much of an
expert on xy-pic.  I'd very much appreciate any suggestions.

Thanks very much,

Roger

********************************

Roger Hart
Assistant Professor, Departments of History and Asian Studies
University of Texas at Austin

email: rhart at mail.utexas.edu
http://uts.cc.utexas.edu/~rhart

*********************************

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