Squiggly arrow in xypic giving error in LyX

Question

I am trying to compile \xymatrix{A\ar@{\sim>}[r] & B} in LyX and I get the following error message:

How can I fix this? The code compiles in ERT, just not in the native xypic mathmode.

Here is a link to MWE.lyx

Answer 1

Your problem is that the xypic package requires some special characters (in particular the tilde ~), which is automatically rewritten by the math editor in LyX. It is somewhat cumbersome to make LyX insert a true tilde into the source code.

But this is a case where the LyX "Macro" feature comes in handy.

1. Go to Insert -> Math -> Macro.
2. Write \sqarrow instead of \newmacroname.
3. Then you copy the text \ar@{~>}[r], and paste it directly into the TeX field of the LyX macro.
4. Finally, in the LyX field of the macro, enter some symbol that resemble the output symbol, such as ~~> or \rightarrow.

You have now created a macro \sqarrow for the squiggly arrow, which you can use directly in the LyX math editor.

For the record, LyX rewrites this macro as \global\long\def\sqarrow{\ar@{~>}[r]} in the LaTeX source code.

Answer 2

The shape input of \xymatrix in \ar@{shape}[direction] does not use mathmode and uses its own interpreter to recognize types of arrow shapes. The input is independent of the environment, and works both in textmode and mathmode:

\documentclass{article}
\usepackage[all,cmtip]{xy} % include cmtip or your arrow will be ugly

\begin{document}
\xymatrix{A\ar@{~>}[r] & B}

\begin{equation}
\xymatrix{A\ar@{~>}[r] & B}
\end{equation}
\end{document}