# [Xy-pic] Compilation error:

Lars Peter Cleary lc at publius.ch
Thu Dec 13 15:33:38 CET 2007

Dear Ross

For my setup I also needed to add $to indicate mathematical formulas. Below the final code for the tree, it's a Markow-event-tree: \xymatrix{ & & & & {\circ} \ar@{-}[dll]_{$\frac{1}{2}$} \ar@{-}[drr]^{$\frac{1}{2}$} & & & & \\ & & *+[F]\txt{L1} \ar@{-}[dl]_{$\frac{1}{2}$} \ar@{-}[d]^{$\frac{1}{2}$} & & & & *+[F]\txt{L2} \ar@{-}[d]_{$\frac{1}{4}$} \ar@{-}[dr]^{$\frac{3}{4}$} & & \\ & *+[o][F-]\txt{G} \ar@{-}[d]_1 & *+[o][F-]\txt{V} \ar@{-}[d]^1 & & & & *+[o][F-]\txt{G} \ar@{-}[d]_1 & *+[o][F-]\txt{V} \ar@{-}[d]^1 & \\ & *+[F]\txt{L1} \ar@{-}[dl]_{$\frac{1}{2}$} \ar@{-}[d]^{$\frac{1}{2}$} & *+[F]\txt{L2} \ar@{-}[d]_{$\frac{1}{4}$} \ar@{-}[dr]^{$\frac{3}{4}$} & & & & *+[F]\txt{L2} \ar@{-}[dl]_{$\frac{1}{4}$} \ar@{-}[d]^{$\frac{3}{4}$} & *+[F]\txt{L1} \ar@{-}[d]_{$\frac{1}{2}$} \ar@{-}[dr]^{$\frac{1}{2}\$} & \\
*+[o][F-]\txt{G+} & *+[o][F-]\txt{V} & *+[o][F-]\txt{G+} &
*+[o][F-]\txt{V} & & *+[o][F-]\txt{G+} & *+[o][F-]\txt{V} &
*+[o][F-]\txt{G+} & *+[o][F-]\txt{V}
}

If the following is of any interest:
My setup is Windows XP, MikTex 2.7 (all packages) and GPL ghostscript 8.61.
My editor is Eclipse (3.3.1.1) with the TeXlipse plugin (1.2.1).
This setup works very well, by the way.

For the math I use following packages:
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{amsfonts}
\usepackage[all]{xy}
\usepackage{xytree}

Thanks a lot for the pointer, Ross, that was very helpful!

Kind regards
Lars

On 12/13/07, Ross Moore <ross at ics.mq.edu.au> wrote:
> Hello Lars,
>
> On 12/12/2007, at 10:20 PM, Lars Peter Cleary wrote:
>
> > Hi all
> >
> > I have some trouble compiling this bit of added code (without it it
> > works):
> >
> > \xymatrix{
> >  & & & & & & & {\circ} \ar@{-}[dl]_\frac{1}{2} \ar@{-}[dr]^\frac{1}{2}
>
> You cannot set a complicated object, such as a fraction,
> as a label in this way. It has to be:
>
>     \ar@{-}[dl]_{\frac{1}{2}}  \ar@{-}[dr]^{\frac{1}{2}}
>
> using extra braces.
> Otherwise the  \frac  will end up being used in a place
> quite apart from its arguments, thus triggering the kind
> of messages that you are seeing.
>
>
> > & & & & & & & \\
> >  & & & *+[F]\txt{L1} \ar@{-}[dl]_\frac{1}{2} \ar@{-}[dr]^\frac{1}{2} &
> > & & & & & & & *+[F]\txt{L2} \ar@{-}[dl]_\frac{1}{4}
> > \ar@{-}[dr]^\frac{3}{4} & & & \\
> >  & & *+[o][F-]\txt{G} \ar@{-}[dl]_1 \ar@{-}[dr]^1 & & *+[o][F-]\txt{V}
> > \ar@{-}[dl]_1 \ar@{-}[dr]^1 & & & & & &
> >  *+[o][F-]\txt{G} \ar@{-}[dl]_1 \ar@{-}[dr]^1 & & *+[o][F-]\txt{V}
> > \ar@{-}[dl]_1 \ar@{-}[dr]^1 & & \\ & *+[F]\txt{L1}
> > \ar@{-}[dl]_\frac{1}{2} \ar@{-}[dr]^\frac{1}{2} & & & &
> >  *+[F]\txt{L2} \ar@{-}[dl]_\frac{1}{4} \ar@{-}[dr]^\frac{3}{4} & & &
> > *+[F]\txt{L2} \ar@{-}[dl]_\frac{1}{4}
> >  \ar@{-}[dr]^\frac{3}{4} & & & & *+[F]\txt{L1} \ar@{-}[dl]_\frac{1}{2}
> > \ar@{-}[dr]^\frac{1}{2} & \\
> > *+[o][F-]\txt{G} & & *+[o][F-]\txt{V} & & *+[o][F-]\txt{G} &
> > *+[o][F-]\txt{V} & & *+[o][F-]\txt{G} & & *+[o][F-]\txt{V}
> > & & *+[o][F-]\txt{G} & & *+[o][F-]\txt{V}
> > }
>
> Put braces around all the  \frac  constructions, and it all
> compiles just fine --- though the resulting tree diagram makes
> no sense to me, presumably because it is incomplete at this stage.
>
>
> Hope this helps,
>
>        Ross Moore
>
>
> >
> > The error messages I get from the console:
> > Argument of \frac has an extra }. } (followed by: )
> > Paragraph ended before \frac was complete. } (followed by: )
> >
> > The lines indicated are the ones of the last bracket closing
> > '\xymatrix{}'.
> >
> >
> >
> > I tried omitting the fractions, then it compiles (some formatting
> > corrections are needed though, I'll sort that later.).
> >
> >
> >
> > Does anybody see an obvious error in my code?
> >
> > Thanks and kind regards
> > Lars
> > _______________________________________________
> > xy-pic mailing list
> > http://tug.org/mailman/listinfo/xy-pic
>
> ------------------------------------------------------------------------
> Ross Moore                                         ross at maths.mq.edu.au
> Mathematics Department                             office: E7A-419
> Macquarie University                               tel: +61 +2 9850 8955
> Sydney, Australia  2109                            fax: +61 +2 9850 8114
> ------------------------------------------------------------------------
>
>
>