4

I use xypics for diagrams, but I don't know how to put the dashed line in the diagram below. Search didn't find much. Can anybody here help?

Big Diagram

h__
  • 821
  • I believe that the only possibility is to insert a new column from the first line to the last one, without entries. – Sigur Feb 08 '13 at 23:08

3 Answers3

9

Here's a way to do it without putting an extra column into the diagram. The dashed line is again inserted as a dashed arrow with no head or tail, i.e., \ar@{--}, but we'll specify both the source and the target of the arrow. In addition, both the source and the target of the arrow will be displaced from one of the nodes. The actual specification of the dashed line is

\ar@{--}[]+<3.5em,0em>;[dddd]+<3.5em,0em>

Note the semicolon; that means that the source is the thing before it and the target is the thing after it. The source is thus []+<3.5em,0em>. Since [] denotes the current node, the source is the point 3.5em to the right and 0em down from the current node.

Similarly, the target of the arrow is [dddd]+<3.5em,0em>, which means the point 3.5em to the right and 0em down from the node [dddd].

Here's a complete latex file:

\documentclass{article}
\usepackage[cmtip,all]{xy}
\begin{document}
\thispagestyle{empty}
\begin{displaymath}
  \xymatrix  {
    && 0\ar[d] \ar@{--}[]+<3.5em,0em>;[dddd]+<3.5em,0em>
    & 0\ar[d]
    &  0\ar[d]\\
    & 0\ar[d] \ar[r]
    & \Gamma^n\Omega^1 \ar[d] \ar[r]^-{d}
    & \Gamma^{n-1}\Omega^1\otimes\Omega^1\ar[d] \ar[r]^{d}
    & \Gamma^{n-2}\Omega^1\otimes\Omega^2 \ar[d] \ar[r]
    & \cdots   \\
    0 \ar[r]
    & A\ar[d]_{Id} \ar[r]^{d^1}
    & P^n\ar[d] \ar[r]^-{D}
    & P^{n-1}\otimes \Omega^1\ar[d] \ar[r]^{D}
    & P^{n-2}\otimes \Omega^2\ar[d] \ar[r] & \cdots \\ 
    0 \ar[r]
    & A\ar[d]_{Id} \ar[r]^{d^1}
    & P^{n-1}\ar[d] \ar[r]^-{D}
    & P^{n-2}\otimes \Omega^1\ar[d] \ar[r]^{D}
    & P^{n-3}\otimes \Omega^2\ar[d] \ar[r]
    & \cdots \\  
    & 0
    & 0
    & 0
    & 0
  }
\end{displaymath}
\end{document}

It produces xy-pic diagram

David Carlisle
  • 757,742
Phil Hirschhorn
  • 8,942
  • Nice. Is there also a way to specify 3.5em as half the column width? – bodo Feb 09 '13 at 07:20
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    @canaaerus: Sorry, I don't know how to refer to the column width, except for the command that can set it. I found the 3.5em by trial and error. – Phil Hirschhorn Feb 09 '13 at 14:05
4

I believe that the only possibility is to insert a new column from the first line to the last one, without entries.

You can control the space between columns changing the value 2em.

Probably it is not possible to change the space only for some columns.

\[ 
\xymatrix@C=2em@R=2em{ &  & 0\ar[d] & \ar@{--}[dddd] & 0\ar[d] &  0\ar[d] &  &  \\ & 0\ar[d] \ar[r]  & \Gamma^n\Omega^1 \ar[d] \ar[rr]^{d} && \Gamma^{n-1}\Omega^1\otimes\Omega^1\ar[d] \ar[r]^{d}& \Gamma^{n-2}\Omega^1\otimes\Omega^2 \ar[d] \ar[r]& \cdots   \\  0 \ar[r] & A\ar[d]_{Id} \ar[r]^{d^1} & P^n\ar[d] \ar[rr]^{D} && P^{n-1}\otimes \Omega^1\ar[d] \ar[r]^{D} & P^{n-2}\otimes \Omega^2\ar[d] \ar[r] & \cdots \\ 
 0 \ar[r] & A\ar[d]_{Id} \ar[r]^{d^1} & P^{n-1}\ar[d] \ar[rr]^{D} && P^{n-2}\otimes \Omega^1\ar[d] \ar[r]^{D} & P^{n-3}\otimes \Omega^2\ar[d] \ar[r] & \cdots \\  
 & 0 & 0 && 0 & 0 &  
  }  \]

enter image description here

Sigur
  • 37,330
0

You can use \save \restore in matrix. For example:

\xymatrix{ ..... &  \save "1,1";"1,2" **@{} ?(0.5) ;p+/d/ ?!{"2,1";"2,2"} **@{--} \restore}

Detailed code description follows:

  • "1,1";"1,2" **@{} draws empty line from element "1,1" to element "1,2".
  • ?(0.5) moves c to the middle of the empty line.
  • ;p+/d/ set up p-c to down direction
  • ?!{"2,1";"2,2"} moves point c to the intersection of p-c and line "2,1";"2,2"
  • **@{--} draws dashed line

You should not forget to insert \shorthandoff{"} in LaTeX.

Stefan Pinnow
  • 29,535
Demid Smirnov
  • 1