# Setting row dimension half default column dimension in xymatrix environment

Consider the following MWE:

\documentclass{article}
\usepackage[all]{xy}

\begin{document}
$$\xymatrix{ \bullet \ar[r]\ar[d] & \bullet\\ \bullet }$$
\end{document}


I know that I can adjust row and column dimension with @R or @C. My question is: How can I set the row dimension equal to half the default column dimension? I.e. without affecting the column dimension?

• @R=4pc @C=2pc – egreg Dec 2 '17 at 22:14
• @egreg Ahh..maybe I should ask differently: What is the default value? Then I can simply put it like this. – TheGeekGreek Dec 2 '17 at 22:17

According to section 26.3 of the Xy-pic reference manual (texdoc xyrefer) the default values for row and column separation are both equal to 2pc.

You can set the row separation for a single matrix by @R=<dimen>, @R+<dimen> or @R-<dimen>. Similarly, C is for the column separation.

\documentclass{article}
\usepackage[all,cmtip]{xy}

\begin{document}

\xymatrix{
A \ar[r] \ar[d] & B \ar[d] \\
C \ar[r] & D
}
\xymatrix@R=2pc@C=2pc{
A \ar[r] \ar[d] & B \ar[d] \\
C \ar[r] & D
}
\xymatrix@C=1pc{
A \ar[r] \ar[d] & B \ar[d] \\
C \ar[r] & D
}

\end{document}