General ⇒ Numbered XY-pic equations

[Annabel]

Hi all

I am using XYpic to create chemical reaction schemes, e.g.:

Code: Select all

\begin{displaymath}
    \xymatrix{
                          & B        & \\
        A \ar[ur] \ar[dr] &          & \\
                          & C  \ar[r]& D}
\end{displaymath}

I wish to number them, because they should be treated as any other equation. However,

Code: Select all

\begin{equation}
    \xymatrix{
                          & B        & \\
        A \ar[ur] \ar[dr] &          & \\
                          & C  \ar[r]& D}
\end{equation}

prints the equations at the top right of the line (box of the equation). Is there any way to alter the position of the equation number (either at the center, or in some rare occasions, at the bottom right)?

Thanks a lot!

[Stefan Kottwitz]

Hi Annabel,

you could use the split environment to get a vertically centered tag:

Code: Select all

\begin{equation}
\begin{split}
    \xymatrix{
                          & B        & \\
        A \ar[ur] \ar[dr] &          & \\
                          & C  \ar[r]& D}
\end{split}
\end{equation}

A bottom aligned number could be achieved using a minipage with b option (\begin{minipage} ...).

Stefan

[Annabel]

Thanks, The split evironment is a great help for vertically centered numbers.

I was not able to put the number at the bottom. Is there a specific order of the latex commands? Now I have:

Code: Select all

\begin{equation}
\begin{minipage}[b]{7cm}
	    \xymatrix{
	                          & B        & \\
	        A \ar[ur] \ar[dr] &          & \\
	                          & C  \ar[r]& D}
\end{minipage}
\end{equation}

[Stefan Kottwitz]

Hi Annabel,

there's a trick: insert

Code: Select all

\vspace{0pt}

right before the end of the minipage. For an explanation have a look at Vertical alignment of graphics, the approach desribed there works also for xymatrix.

Stefan